Transmission method

ABSTRACT

Provided is a transmission method that contributes to an increase in data reception quality when iterative detection is performed at a receive apparatus side. A transmit apparatus alternates between two types of modulation scheme that each shift amplitude and phase, performs mapping to constellation points according to a selected modulation scheme, and transmits a modulated signal obtained by mapping.

TECHNICAL FIELD Related Applications

All content disclosed in the claims, descriptions, drawings, andabstracts of Japanese Patent Application 2013-084269, Japanese PatentApplication 2013-084270, and Japanese Patent Application 2013-084271,filed Apr. 12, 2013; and Japanese Patent Application 2013-099605,Japanese Patent Application 2013-099606, and Japanese Patent Application2013-099607, filed May 9, 2015, is incorporated into the presentapplication.

The present invention is related to transmission methods of signals forperforming iterative detection at a receive apparatus side.

BACKGROUND ART

Conventionally, as in Non-Patent Literature 1, with respect toquadrature amplitude modulation (QAM), studies have been carried outinto improvements in reception quality of data for bit interleaved codedmodulation with iterative detection (BICM-ID) by changing aspects of bitlabelling.

CITATION LIST Patent Literature Patent Literature 1

-   Japanese Patent Application Publication 2013-16953

Non-Patent Literature Non-Patent Literature 1

-   A. Chindapol and J. A. Ritcey, “Design, analysis, and performance    evaluation for BICM-ID with square QAM constellations in Rayleigh    fading channels” IEEE Journal on selected areas in communication,    vol. 19, no. 5, pp. 944-957, May 2001

Non-Patent Literature 2

-   Transmission System for Advanced Wide Band Digital Satellite    Broadcasting, ARIB Standard STD-B44, Ver. 1.0, July 2009

SUMMARY OF INVENTION Technical Problem

Modulation schemes other than QAM, such as amplitude phase shift keying(APSK), may be used due to peak-to-average power ratio (PAPR)limitations, etc., and therefore application to communication/broadcastsystems of the techniques of Non-Patent Literature 1 that relate to QAMlabelling may be difficult.

The present invention has an aim of providing a transmission method thatcontributes to improvement in data reception quality when iterativedetection is performed on a receive apparatus side in, for example, acommunication/broadcast system.

Solution to Problem

A transmission method pertaining to the present invention is applicableto a transmit apparatus for transmitting data by modulation schemes thatshift amplitude and phase, the transmit apparatus comprising: a selectorthat alternately selects a first modulation scheme and a secondmodulation scheme for each symbol, a constellation and bit labelling ofeach constellation point of the first modulation scheme being differentto a constellation and bit labelling of each constellation point of thesecond modulation scheme; a mapper that performs mapping by usingconstellation points of a selected modulation scheme; and a transmitterthat transmits a modulated signal obtained by the mapping, wherein thefirst modulation scheme is 16 amplitude phase shift keying (APSK)modulation that arranges, in a first in-phase (I)-quadrature-phase (Q)plane, 16 constellation points composed of four constellation points onthe circumference of a first inner circle and twelve constellationpoints on the circumference of a first outer circle, the first innercircle and the first outer circle being concentric circles, wherein:when the 16 constellation points are divided into four groups eachcomposed of one constellation point on the circumference of the firstinner circle and three constellation points on a portion of thecircumference of the first outer circle in a direction from the originof the first I-Q plane to the one constellation point, only one bit isdifferent in bit labelling between each pair, within each group, ofconstellation points adjacent on the circumference of the first outercircle, and only one bit is different in bit labelling between eachpair, within each group, of each constellation point on thecircumference of the first inner circle and each constellation point atone of two ends of each portion of the circumference of the first outercircle; and only one bit is different in bit labelling between eachpair, between different groups, of constellation points that are closestto each other on the first I-Q plane on the circumference of the firstouter circle, and only one bit is different in bit labelling betweeneach pair, between different groups, of constellation points that areclosest to each other on the first I-Q plane on the circumference of thefirst inner circle, and the second modulation scheme is 16APSKmodulation that arranges, in a second I-Q plane, 16 constellation pointscomposed of eight constellation points on the circumference of a secondinner circle and eight constellation points on the circumference of asecond outer circle, the second inner circle and the second outer circlebeing concentric circles, wherein: when the 16 constellation points aredivided into a first group composed of the eight constellation points onthe circumference of the second inner circle and a second group composedof the eight constellation points on the circumference of the secondouter circle, only one bit is different in bit labelling between eachpair, within the first group, of constellation points that are adjacenton the circumference of the second inner circle, and only one bit isdifferent in bit labelling between each pair, within the second group,of constellation points that are adjacent on the circumference of thesecond outer circle.

Advantageous Effects of Invention

The transmission method pertaining to the present invention, inparticular when applied to a communication/broadcast system using errorcorrection code having a high error correction capacity, such as lowdensity parity check (LDPC) code and turbo code such as duo-binary turbocode, can contribute to improving data reception quality at a receiveapparatus side at the time of initial detection or when iterativedetection is performed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example of input/output power properties of apower amplifier mounted on a transmit apparatus.

FIG. 2 illustrates a configuration example of a communication systemusing a BICM-ID scheme.

FIG. 3 illustrates an example of input and output of a coder of atransmit apparatus.

FIG. 4 illustrates an example of a bit-reduction encoder of a transmitapparatus.

FIG. 5 illustrates an example of a bit-reduction decoder of a receiveapparatus.

FIG. 6 illustrates an example of input and output of a XOR section of abit-reduction decoder.

FIG. 7 illustrates a configuration of a transmit apparatus.

FIG. 8 illustrates a constellation of (12,4)16APSK.

FIG. 9 illustrates a constellation of (8,8)16APSK.

FIG. 10 illustrates a block diagram related to generation of a modulatedsignal.

FIG. 11 illustrates frame configuration of a modulated signal.

FIG. 12 illustrates an example of data symbols.

FIG. 13 illustrates an example of pilot symbols.

FIG. 14 illustrates an example of labelling of (12,4)16APSK.

FIG. 15 illustrates an example of labelling of (12,4)16APSK.

FIG. 16 illustrates an example of labelling of (8,8)16APSK.

FIG. 17 illustrates an example of a constellation of (8,8)16APSK.

FIG. 18 illustrates a schematic of a transmit signal frame of advancedwide band digital satellite broadcasting.

FIG. 19 illustrates a configuration of a receive apparatus.

FIG. 20 illustrates examples of arrangement of modulation schemes.

FIG. 21 illustrates an example of arrangement of modulation schemes.

FIG. 22 illustrates an example configuration of stream type/relativestream information.

FIG. 23 illustrates examples of arrangement of modulation schemes.

FIG. 24 illustrates an example of arrangement of symbols.

FIG. 25 illustrates examples of constellations of 32APSK.

FIG. 26 illustrates an example of constellation and labelling ofNU-16QAM.

FIG. 27 illustrates a schematic of wide band digital satellitebroadcasting.

FIG. 28 illustrates a block diagram related to ring ratio determination.

FIG. 29 is a diagram for describing a bandlimiting filter.

FIG. 30 illustrates an example of a constellation of (4,8,4)16APSK.

FIG. 31 illustrates an example of a constellation of (4,8,4)16APSK.

FIG. 32 illustrates an example of a constellation of (4,8,4)16APSK.

FIG. 33 illustrates an example of arrangement of symbols.

FIG. 34 illustrates an example of arrangement of symbols.

FIG. 35 illustrates an example of arrangement of symbols.

FIG. 36 illustrates an example of arrangement of symbols.

FIG. 37 illustrates examples of arrangement of modulation schemes.

FIG. 38 illustrates an example of arrangement of modulation schemes.

FIG. 39 illustrates an example configuration of a transmit station.

FIG. 40 illustrates an example configuration of a receive apparatus.

FIG. 41 illustrates an example configuration of a transmit station.

FIG. 42 illustrates an example configuration of a transmit station.

FIG. 43 illustrates an example configuration of a transmit station.

FIG. 44 illustrates an example of frequency allocation of signals.

FIG. 45 illustrates an example configuration of a satellite.

FIG. 46 illustrates an example configuration of a satellite.

FIG. 47 illustrates an example configuration of extended information.

FIG. 48 illustrates an example of signaling.

FIG. 49 illustrates an example of signaling.

FIG. 50 illustrates an example of signaling.

FIG. 51 illustrates an example of signaling.

FIG. 52 illustrates an example of signaling.

FIG. 53 illustrates an example of signaling.

FIG. 54 illustrates an example of signaling.

FIG. 55 illustrates an example of signaling.

FIG. 56 illustrates an example of signaling.

FIG. 57 illustrates an example of signaling.

EMBODIMENTS Developments that LED to an Embodiment Pertaining to thePresent Invention

Typically, in a communication/broadcast system, in order to reduce powerconsumption of an amplifier for transmission and reduce errors in dataat a receiver, a modulation scheme is preferred for which thepeak-to-average power ratio (PAPR) is low and data reception quality ishigh.

In particular, in satellite broadcasting, in order to reduce powerconsumption of an amplifier for transmission, use of a modulation schemefor which PAPR is low is preferred, and (12,4) 16 amplitude phase shiftkeying (16APSK) is commonly used as a modulation scheme in which 16constellation points exist in an in-phase (I)-quadrature-phase (Q)plane. Note that a constellation in an I-Q plane of (12,4) 16APSKmodulation is described in detail later.

However, when (12,4) 16APSK is used in a communication/broadcast system,data reception quality of a receiver is sacrificed, and therefore thereis a need to use, in satellite broadcasting, a modulationscheme/transmission method in which PAPR is low and data receptionquality is high.

In order to improve reception quality, a modulation scheme having goodbit error ratio (BER) properties may be considered. However, use of amodulation scheme having excellent BER properties is not necessarily thebest solution in every case. This point is explained below.

For example, assume that when a modulation scheme #B is used, asignal-to-noise power ratio (SNR) of 10.0 dB is required to obtain a BERof 10⁵, and when a modulation scheme #A is used, an SNR of 9.5 dB isrequired to obtain a BER of 10⁻⁵.

When a transmit apparatus uses the modulation scheme #A or themodulation scheme #B at the same average transmission power, a receiveapparatus can obtain a gain of 0.5 dB (10.0−9.5) by using the modulationscheme #B.

However, when the transmit apparatus is installed on a satellite, PAPRbecomes an issue. Input/output power properties of a power amplifierinstalled on the transmit apparatus are illustrated in FIG. 1.

Here, when the modulation scheme #A is used, PAPR is assumed to be 7.0dB, and when the modulation scheme #B is used, PAPR is assumed to be 8.0dB.

The average transmit power when the modulation scheme #B is used is 1.0(8.0-7.0) dB less than the average transmit power when the modulationscheme #A is used.

Accordingly, when the modulation scheme #B is used, 0.5−1.0=−0.5, andtherefore the receive apparatus obtains a gain of 0.5 dB when themodulation scheme #A is used.

As described above, use of a modulation scheme that excels in terms ofBER properties is not preferred in such a case. The present embodimenttakes into consideration the points above.

Thus, the present embodiment provides a modulation scheme/transmissionmethod for which PAPR is low and data reception quality is high.

Further, in Non-Patent Literature 1, consideration is given to how tolabel bits and how that improves data reception quality when bitinterleaved coded modulation with iterative detection (BICM-ID) is usedwith respect to quadrature amplitude modulation (QAM). However, in somecases it is difficult to achieve the described effects using theapproach used in Non-Patent Literature 1 (how to label bits with respectto QAM) for error correction code having high error correction capacity,such as low-density parity-check (LDPC) code and turbo code such asduo-binary turbo code.

In the present embodiment, a transmission method is provided forobtaining high data reception quality when error correction code havinghigh error correction capacity is used, such as LDPC code and turbocode, and iterative detection (or detection) is performed at a receiveapparatus side.

The following is a detailed description of embodiments of the presentinvention, with reference to the drawings.

Embodiment 1

The following describes in detail a transmission method, transmitapparatus, reception method, and receive apparatus of the presentembodiment.

Prior to this description, an overview of a communication system using aBICM-ID scheme at a receive apparatus side is described below.

<BICM-ID>

FIG. 2 illustrates an example of a communication system using a BICM-IDscheme.

The following describes BICM-ID when a bit-reduction encoder 203 and abit-reduction decoder 215 are used, but iterative detection may beimplemented in cases without the bit-reduction encoder 203 and thebit-reduction decoder 215.

A transmit apparatus 200 includes a coder 201, an interleaver 202, thebit-reduction encoder 203, a mapper 204, a modulator 205, a radiofrequency (RF) transmitter 206, and a transmit antenna 207.

A receive apparatus 210 includes a receive antenna 211, an RF receiver212, a demodulator 213, a de-mapper 214, the bit-reduction decoder 215,a de-interleaver 216, a decoder 217, and an interleaver 218.

FIG. 3 illustrates an example of input/output bits of the coder 201 ofthe transmit apparatus 200.

The coder 201 performs coding at a coding rate R₁, and when N_(info)information bits are inputted, the coder 201 outputs N_(info)/R₁ codedbits.

FIG. 4 illustrates an example of the bit-reduction encoder 203 of thetransmit apparatus 200.

The present example of the bit-reduction encoder 203, when a bitsequence b(b₀-b₇) of eight bits is inputted from the interleaver 202,performs a conversion that involves reducing the number of bits, andoutputs a bit sequence m(m₀-m₃) of four bits to the mapper 204. In FIG.4, “[+]” indicates an exclusive OR (XOR) section.

That is, the present example of the bit-reduction encoder 203 has: abranch that connects an input for bit b₀ to an output for bit m₀ via anXOR section; a branch that connects inputs for bits b₁ and b₂ to anoutput for bit m₁ via an XOR section; a branch that connects inputs forbits b₃ and b₄ to an output for bit m₂ via an XOR section; and a branchthat connects inputs bits b₅, b₆ and b₇ to an output for bit m₃ via anXOR section.

FIG. 5 illustrates an example of the bit-reduction decoder 215 of thereceive apparatus 210.

The present example of the bit-reduction decoder 215, when a loglikelihood ratio (LLR) L(m₀)-L(m₃) for a bit sequence m(m₀-m₃) of fourbits is inputted from the de-mapper 214, performs a conversion thatinvolves restoring the original number of bits, and outputs an LLRL(b₀)-L(b₇) for a bit sequence b(b₀-b₇) of eight bits. The LLRL(b₀)-L(b₇) for the bit sequence b(b₀-b₇) of eight bits is inputted tothe decoder 217 via the de-interleaver 216.

Further, the bit-reduction decoder 215, when an LLR L(b₀)-L(b₇) for abit sequence b(b₀-b₇) of eights bits is inputted from the decoder 217via the interleaver 218, performs a conversion that involves reducingthe number of bits, and outputs an LLR L(m₀)-L(m₃) for a bit sequencem(m₀-m₃) of four bits to the de-mapper 214.

In FIG. 5, “[+]” indicates an XOR section. That is, the present exampleof the bit-reduction decoder 215 has: a branch that connects aninput/output for L(b₀) to an input/output for L(m₀) via an XOR section;a branch that connects inputs/outputs for L(b₁) and L(b₂) to aninput/output for L(m₁) via an XOR section; a branch that connectsinputs/outputs for L(b₃) and L(b₄) to an input/output for L(m₂) via anXOR section; and a branch that connects inputs/outputs for L(b₅), L(b₆)and L(b₇) to an input/output for L(m₃) via an XOR section.

In the present example, with respect to a bit sequence b(b₀-b₇) of eightbits prior to bit reduction, bit b₀ is a least significant bit (LSB) andbit b₇ is a most significant bit (MSB). Further, with respect to a bitsequence m(m₀-m₃) of four bits after bit reduction, bit m₀ is an LSB andbit m₃ is an MSB.

FIG. 6 illustrates input/output of an XOR section, in order to describeoperation of the bit-reduction decoder 215.

In FIG. 6, bits u₁ and u₂ are connected to bit u₃ via an XOR section.Further, LLRs L(u₁), L(u₂), and L(u₃) for bits u₁, u₂ and u₃ areillustrated. A relationship between L(u₁), L(u₂), and L(u₃) is describedlater.

The following describes processing flow with reference to FIG. 2 to FIG.6. At the transmit apparatus 200 side, transmit bits are inputted to thecoder 201, and (error correction) coding is performed. For example, asillustrated in FIG. 3, when a coding rate of error correction code usedin the coder 201 is R₁, and N_(info) information bits are inputted tothe coder 201, N_(info)/R₁ bits are outputted from the coder 201.

A signal (data) encoded by the coder 201 is, after interleavingprocessing by the interleaver 202 (permutation of data), inputted to thebit-reduction encoder 203. Subsequently, as described with reference toFIG. 3, bit number reduction processing is performed by thebit-reduction encoder 203. Note that bit number reduction processingneed not be implemented.

A signal (data) on which bit reduction processing has been performedundergoes mapping processing at the mapper 204. The modulator 205performs processing such as conversion of a digital signal to an analogsignal, bandlimiting, and quadrature modulation (and multi-carriermodulation such as orthogonal frequency division multiplexing (OFDM) mayalso be implemented) on a signal on which mapping processing has beenperformed.

A signal that has undergone this signal processing is transmittedwirelessly from, for example, the transmit antenna 207, via transmitradio frequency (RF) processing (206) in which transmit processing isperformed.

At the receive apparatus 210 side, the RF receiver 212 performsprocessing such as frequency conversion and quadrature demodulation on asignal (radio signal from a transmit apparatus side) received by thereceive antenna 211, generates a baseband signal, and outputs to thedemodulator 213.

The demodulator 213 performs processing such as channel estimation anddemodulation, generates a signal after demodulation, and outputs to thede-mapper 214. The de-mapper 214 calculates an LLR for each bit, basedon the receive signal inputted from the demodulator 213, noise powerincluded in the receive signal, and prior information obtained from thebit-reduction decoder 215.

The de-mapper 214 performs processing with respect to a signal mapped bythe mapper 204. In other words, the de-mapper 214 calculates LLRs for abit sequence (corresponding to the bit sequence m illustrated in FIG. 4and FIG. 5) after bit number reduction processing is performed at atransmit apparatus side.

In a subsequent step of decoding processing (decoder 217) processing isperformed with respect to all coding bits (corresponding to the bitsequence b illustrated in FIG. 4 and FIG. 5), and therefore conversionof LLRs post-bit-reduction (LLRs pertaining to processing of thede-mapper 214) to LLRs pre-bit-reduction (LLRs pertaining to processingof the decoder 217) is required.

Thus, at the bit-reduction decoder 215, LLRs post-bit-reduction inputtedfrom the de-mapper 214 are converted to LLRs corresponding to a timepre-bit-reduction (corresponding to bit sequence b illustrated in FIG. 4and FIG. 5). Details of processing are described later.

An LLR calculated at the bit-reduction decoder 215 is inputted to thedecoder 217 after de-interleaving processing by the de-interleaver 216.The decoder 217 performs decoding processing on the basis of inputtedLLRs, and thereby re-calculates the LLRs. LLRs calculated by the decoder217 are fed back to the bit-reduction decoder 215 after interleavingprocessing by the interleaver 218. The bit-reduction decoder 215converts LLRs fed back from the decoder 217 to LLRs post-bit-reduction,and inputs the LLRs post-bit-reduction to the de-mapper 214. Thede-mapper 214 again calculates an LLR for each bit, based on the receivesignal, noise power included in the receive signal, and priorinformation obtained from the bit-reduction decoder 215.

In a case in which bit number reduction processing is not performed at atransmit apparatus side, the processing specific to the bit-reductiondecoder 215 is not performed.

By repeatedly performing the above processing, finally a desired decodedresult is obtained.

The following describes LLR calculation processing at the de-mapper 214.

An LLR outputted from the de-mapper 214 when a bit sequence b(b₀, b₁, .. . , b_(N-1)) of N (N being an integer greater than or equal to one)bits is allocated to M (M being an integer greater than or equal to one)symbol points S_(k)(S₀, S₁, . . . , S_(M-1)) is considered below.

When a receive signal is y, an i-th (i being an integer from zero toN−1) bit is b_(i), and an LLR for b_(i) is L(b_(i)), Math (1) holdstrue.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 1} \right\rbrack & \; \\\begin{matrix}{{L\left( b_{i} \right)} = {\log \frac{p\left( {b_{i} = {0y}} \right)}{p\left( {b_{i} = {1y}} \right)}}} \\{= {\log \frac{{p\left( {{yb_{i}} = 0} \right)}{{p\left( {b_{i} = 0} \right)}/{p(y)}}}{{p\left( {{yb_{i}} = 1} \right)}{{p\left( {b_{i} = 1} \right)}/{p(y)}}}}} \\{= {{\log \frac{p\left( {{yb_{i}} = 0} \right)}{p\left( {{yb_{i}} = 1} \right)}} + {\log \frac{p\left( {b_{i} = 0} \right)}{p\left( {b_{i} = 1} \right)}}}}\end{matrix} & \left( {{Math}\mspace{14mu} 1} \right)\end{matrix}$

As described later, the first term on the right side of the bottomformula shown in Math (1) is an LLR obtainable from a bit other than ani-th bit, and this is defined as extrinsic information L_(e)(b_(i)).Further, the second term on the right side of the bottom formula shownin Math (1) is an LLR obtainable based on a prior probability of an i-thbit, and this is defined as prior information L_(a)(b_(i)).

Thus, Math (1) becomes Math (2), and transformation to Math (3) ispossible.

[Math 2]

L(b _(i))=L _(e)(b _(i))+L _(a)(b _(i))  (Math 2)

[Math 3]

L _(e)(b _(i))L _(e)(b _(i))−L _(a)(b _(i))  (Math 3)

The de-mapper 214 outputs a processing result of Math (3) as an LLR.

The numerator p(y|b_(i)=0) of the first term on the right side of thebottom formula of Math (1) is considered below.

The numerator p(y|b_(i)=0) is a probability that a receive signal is ywhen b_(i)=0 is known. This is expressed in the productp(y|S_(k))p(S_(k)|b_(i)=0) of “a probability p(S_(k)|b_(i)=0) of asymbol point S_(k) when b_(i)=0 is known,” and “a probability p(y|S_(k))of y when S_(k) is known”. When considering all symbol points, Math (4)holds true.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 4} \right\rbrack & \; \\{{p\left( {{yb_{i}} = 0} \right)} = {\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 0}\; {{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 0} \right)}}}} & \left( {{Math}\mspace{14mu} 4} \right)\end{matrix}$

In the same way, with respect to the denominator p(y|b_(i)=1) of thefirst term on the right side of the bottom formula of Math (1), Math (5)holds true.

Accordingly, the first term on the right side of the bottom formula ofMath (1) becomes Math (6).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 5} \right\rbrack & \; \\{{p\left( {{yb_{i}} = 1} \right)} = {\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 1}{{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 1} \right)}}}} & \left( {{Math}\mspace{14mu} 5} \right) \\\left\lbrack {{Math}\mspace{14mu} 6} \right\rbrack & \; \\\begin{matrix}{{L_{e}\left( b_{i} \right)} = {\log \frac{p\left( {{yb_{i}} = 0} \right)}{p\left( {{yb_{i}} = 1} \right)}}} \\{= {\log \frac{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 0}{{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 0} \right)}}}{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 1}{{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 1} \right)}}}}}\end{matrix} & \left( {{Math}\mspace{14mu} 6} \right)\end{matrix}$

The expression p(y|S_(k)) of Math (6) can be expressed as shown in Math(7) when Gaussian noise of variance σ² is added in the process oftransmitting the symbol point S_(k) to become the receive signal y.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 7} \right\rbrack & \; \\{{p\left( {yS_{k}} \right)} = {\frac{1}{\sqrt{2\; \pi \; \sigma^{2}}}{\exp\left( {- \frac{\left( {y - S_{k}} \right)^{2}}{2\; \sigma^{2}}} \right)}}} & \left( {{Math}\mspace{14mu} 7} \right)\end{matrix}$

Further, the expression p(S_(k)|b_(i)=0) of Math (6) is a probability ofthe symbol point S_(k) when b_(i)=0 is known, and is expressed as aproduct of prior probabilities of bits other than b_(i) that constitutethe symbol point S_(k). When a j-th (j=0, 1, . . . , N−1 (j being aninteger from 0 to N−1)) bit of the symbol point S_(k) is expressed asS_(k)(b_(j)), Math (8) holds true.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 8} \right\rbrack & \; \\{{{S_{k}\left( b_{j} \right)} \in \left\{ {0,1} \right\}}{{p\left( {{S_{k}b_{i}} = 0} \right)} = {\prod\limits_{j \neq i}{p\left( {b_{j} = {S_{k}\left( b_{j} \right)}} \right)}}}} & \left( {{Math}\mspace{14mu} 8} \right)\end{matrix}$

The term p(b_(j)=S_(k)(b_(j))) is considered below.

When L_(a)(b_(j)) is given as prior information, Math (9) is derivedfrom the second term of the right side of the bottom formula of Math(1), and can be transformed to Math (10).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 9} \right\rbrack & \; \\{{L_{a}\left( b_{j} \right)} = {\log \frac{p\left( {b_{j} = 0} \right)}{p\left( {b_{j} = 1} \right)}}} & \left( {{Math}\mspace{14mu} 9} \right) \\\left\lbrack {{Math}\mspace{14mu} 10} \right\rbrack & \; \\{\frac{p\left( {b_{j} = 0} \right)}{p\left( {b_{j} = 1} \right)} = {\exp \left( {L_{a}\left( b_{j} \right)} \right)}} & \left( {{Math}\mspace{14mu} 10} \right)\end{matrix}$

Further, from the relationship p(b_(j)=0)+p(b_(j)=1)=1, Math (11) andMath (12) are derived.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 11} \right\rbrack & \; \\{{p\left( {b_{j} = 0} \right)} = \frac{\exp \left( {L_{a}\left( b_{j} \right)} \right)}{1 + {\exp \left( {L_{a}\left( b_{j} \right)} \right)}}} & \left( {{Math}\mspace{14mu} 11} \right) \\\left\lbrack {{Math}\mspace{14mu} 12} \right\rbrack & \; \\{{p\left( {b_{j} = 1} \right)} = \frac{1}{1 + {\exp \left( {L_{a}\left( b_{j} \right)} \right)}}} & \left( {{Math}\mspace{14mu} 12} \right)\end{matrix}$

Using this, Math (13) is derived, and Math (8) becomes Math (14).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 13} \right\rbrack & \; \\{{p\left( {b_{j} = {S_{k}\left( b_{j} \right)}} \right)} = \frac{\exp \left( {{- {S_{k}\left( b_{j} \right)}}{L_{a}\left( b_{j} \right)}} \right)}{1 + {\exp \left( {- {L_{a}\left( b_{j} \right)}} \right)}}} & \left( {{Math}\mspace{14mu} 13} \right) \\\left\lbrack {{Math}\mspace{14mu} 14} \right\rbrack & \; \\\begin{matrix}{{p\left( {{S_{k}b_{i}} = 0} \right)} = {\prod\limits_{j \neq i}{p\left( {b_{j} = {S_{k}\left( b_{j} \right)}} \right)}}} \\{= {\prod\limits_{j \neq i}\frac{\exp \left( {{- {S_{k}\left( b_{j} \right)}}{L_{a}\left( b_{j} \right)}} \right)}{1 + {\exp \left( {- {L_{a}\left( b_{j} \right)}} \right)}}}}\end{matrix} & \left( {{Math}\mspace{14mu} 14} \right)\end{matrix}$

With respect to p(S_(k)|b_(i)=1), a formula similar to Math (14) isderived. From Math (7) and Math (14), Math (6) becomes Math (15). Notethat as per the condition of Σ, the numerator of S_(k)(b_(i)) is zero,and the denominator of S_(k)(b_(i)) is one.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Math}\mspace{14mu} 15} \right\rbrack} & \; \\\begin{matrix}{{L_{e}\left( b_{i} \right)} = {\log \frac{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 0}{{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 0} \right)}}}{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 1}{{p\left( {yS_{k}} \right)}{p\left( {{S_{k}b_{i}} = 1} \right)}}}}} \\{= {\log \frac{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 0}{\frac{1}{\sqrt{2\; \pi \; \sigma^{2}}}{\exp\left( {- \frac{{{y - S_{k}}}^{2}}{2\; \sigma^{2}}} \right)}{\prod\limits_{j \neq i}\frac{\exp \left( {{- {S_{k}\left( b_{j} \right)}}{L_{a}\left( b_{j} \right)}} \right)}{1 + {\exp \left( {- {L_{a}\left( b_{j} \right)}} \right)}}}}}{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 1}{\frac{1}{\sqrt{2\; \pi \; \sigma^{2}}}{\exp \left( {- \frac{{{y - S_{k}}}^{2}}{2\; \sigma^{2}}} \right)}{\prod\limits_{j \neq i}\frac{\exp \left( {{- {S_{k}\left( b_{j} \right)}}{L_{a}\left( b_{j} \right)}} \right)}{1 + {\exp \left( {- {L_{a}\left( b_{j} \right)}} \right)}}}}}}} \\{= {{\log \frac{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 0}{{\exp\left( {- \frac{{{y - S_{k}}}^{2}}{2\; \sigma^{2}}} \right)}{\sum\limits_{j}{{S_{k}\left( b_{j} \right)}{L_{a}\left( b_{j} \right)}}}}}{{\sum\limits_{{S_{k}{S_{k}{(b_{i})}}} = 1}{\exp \left( {- \frac{{{y - S_{k}}}^{2}}{2\; \sigma^{2}}} \right)}} - {\sum\limits_{j}{{S_{k}\left( b_{j} \right)}{L_{a}\left( b_{j} \right)}}}}} - {L_{a}\left( b_{i} \right)}}}\end{matrix} & \left( {{Math}\mspace{14mu} 15} \right)\end{matrix}$

From the above, in performing the repeated processing of BICM-ID, thede-mapper 214 performs exponential calculation and summation for asymbol point and each bit assigned to the symbol point, thereby seekingnumerators/denominators, and further performs a logarithmic calculation.

The following described processing at the bit-reduction decoder 215.

The bit-reduction decoder 215 performs processing converting LLRspost-bit-reduction that are calculated at the de-mapper 214 to LLRspre-bit-reduction that are required at the decoder 217, and performsprocessing converting LLRs pre-bit-reduction that are calculated at thedecoder 217 to LLRs post-bit-reduction that are required at thede-mapper 214.

At the bit-reduction decoder 215, processing converting LLRspost-bit-reduction is performed at each [+] (each XOR section) in FIG.5, calculation being performed according to bits connected to the [+].

In a configuration as illustrated in FIG. 6, L(u₃) is considered whenL(u₁) and L(u₂) are given, each bit being defined as u₁, u₂, u₃, andeach LLR for the bits being defined as L(u₁), L(u₂), L(u₃).

First, u₁ is considered below.

When L(u₁) is given, Math (16) and Math (17) are derived from Math (11)and Math (12).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 16} \right\rbrack & \; \\{{p\left( {u_{1} = 0} \right)} = \frac{\exp \left( {L\left( u_{1} \right)} \right)}{1 + {\exp \left( {L\left( u_{1} \right)} \right)}}} & \left( {{Math}\mspace{14mu} 16} \right) \\\left\lbrack {{Math}\mspace{14mu} 17} \right\rbrack & \; \\{{p\left( {u_{1} = 1} \right)} = \frac{1}{1 + {\exp \left( {L\left( u_{1} \right)} \right)}}} & \left( {{Math}\mspace{14mu} 17} \right)\end{matrix}$

When u₁=0 is associated with +1 and u₁=1 is associated with −1, theexpected value E[u₁] of u₁ is defined as in Math (18).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 18} \right\rbrack & \; \\\begin{matrix}{{E\left\lbrack u_{1} \right\rbrack} = {{\left( {+ 1} \right){p\left( {u_{1} = 0} \right)}} + {\left( {- 1} \right){p\left( {u_{1} = 1} \right)}}}} \\{= \frac{{\exp \left( {L\left( u_{1} \right)} \right)} - 1}{{\exp \left( {L\left( u_{1} \right)} \right)} + 1}} \\{= {{\tanh \left( \frac{L\left( u_{1} \right)}{2} \right)}\left( {{\Theta \; {\tanh (\chi)}} = \frac{^{\chi} - ^{- \chi}}{^{\chi} + ^{- \chi}}} \right)}}\end{matrix} & \left( {{Math}\mspace{14mu} 18} \right)\end{matrix}$

In FIG. 6, u₃=u₁[+]u₂ and E[u₃]=E[u₁]E[u₂], and therefore whensubstituted into Math (18), Math (19) results, from which Math (20) isderived.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 19} \right\rbrack & \; \\{{\tanh \left( \frac{L\left( u_{3} \right)}{2} \right)} = {{\tanh \left( \frac{L\left( u_{1} \right)}{2} \right)}{\tanh \left( \frac{L\left( u_{2} \right)}{2} \right)}}} & \left( {{Math}\mspace{14mu} 19} \right) \\\left\lbrack {{Math}\mspace{14mu} 20} \right\rbrack & \; \\{{L\left( u_{3} \right)} = {2\; {\tanh^{- 1}\left( {{\tanh \left( \frac{L\left( u_{1} \right)}{2} \right)}{\tanh \left( \frac{L\left( u_{2} \right)}{2} \right)}} \right)}}} & \left( {{Math}\mspace{14mu} 20} \right)\end{matrix}$

The above considers bits u₁, u₂, and u₃, but when generalized to jsignals, Math (21) is derived. For example, in FIG. 5, L(m₃), L(b₆), andL(b₅) are used when determining L(b₇), resulting in Math (22).

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 21} \right\rbrack & \; \\{{L\left( u_{i} \right)} = {2\; {\tanh^{- 1}\left( {\prod\limits_{j{j \neq i}}{\tanh \left( \frac{L\left( u_{j} \right)}{2} \right)}} \right)}}} & \left( {{Math}\mspace{14mu} 21} \right) \\\left\lbrack {{Math}\mspace{14mu} 22} \right\rbrack & \; \\{{L\left( b_{7} \right)} = {2\; {\tanh^{- 1}\left( {\tanh \frac{L\left( m_{3} \right)}{2}\tanh \frac{L\left( b_{6} \right)}{2}\tanh \frac{L\left( b_{5} \right)}{2}} \right)}}} & \left( {{Math}\mspace{14mu} 22} \right)\end{matrix}$

In a case in which bit number reduction processing is not performed at atransmit apparatus side, the specific processing described above is notperformed.

The above describes operations in connection with BICM-ID, but iterativedetection need not be implemented, and signal processing may performdetection only once.

<Transmit Apparatus>

FIG. 7 illustrates a configuration of a transmit apparatus.

A transmit apparatus 700 includes an error correction coder 702, acontrol information generator and mapper 704, an interleaver 706, amapper 708, a modulator 710, and a radio section 712.

The error correction coder 702 receives a control signal and informationbits as input, determines, for example, code length (block length) oferror correction code and coding rate of error correction code based onthe control signal, performs error correction coding on the informationbits based on a determined error correction coding method, and outputsbits after error correction coding to the interleaver 706.

The interleaver 706 receives a control signal and bits post-coding asinput, determines an interleaving method based on the control signal,interleaves (permutes) the bits post-coding, and outputs datapost-interleaving to the mapper 708.

The control information generator and mapper 704 receives a controlsignal as input, generates control information for a receive apparatusto operate (for example, information related to physical layers such asan error correction scheme or modulation scheme used by a transmitapparatus, control information not related to physical layers, etc.)based on the control signal, performs mapping on the controlinformation, and outputs a control information signal.

The mapper 708 receives a control signal and data post-interleaving asinput, determines a mapping method based on the control signal, performsmapping on the data post-interleaving according to the mapping methoddetermined, and outputs a baseband signal in-phase component I andquadrature component Q. Modulation schemes that the mapper 708 iscapable of supporting are, for example, π/2 shift BPSK, QPSK, 8PSK,(12,4)16APSK, (8,8)16APSK, and 32APSK.

Details of (12,4)16APSK, (8,8)16APSK, and details of a mapping methodthat is a feature of the present embodiment are described in detaillater.

The modulator 710 receives a control signal, a control informationsignal, a pilot signal, and a baseband signal as input, determines frameconfiguration based on the control signal, generates, according to theframe configuration, a modulated signal from the control informationsignal, the pilot signal, and the baseband signal, and outputs themodulated signal.

The radio section 712 receives a modulated signal as input, performsprocessing such as bandlimiting using a root roll-off filter, quadraturemodulation, frequency conversion, and amplification, and generates atransmit signal, the transmit signal being transmitted from an antenna.

<Constellation>

The following describes constellations and assignment (labelling) ofbits to each constellation point of (12,4)16APSK and (8,8)16APSK mappingperformed by the mapper 708, which is of importance in the presentembodiment.

As illustrated in FIG. 8, constellation points of (12,4)16APSK mappingare arranged in two concentric circles having different radii (amplitudecomponents) in the I-Q plane. In the present description, among theconcentric circles, a circle having a larger radius R₂ is referred to asan “outer circle” and a circle having a smaller radius R₁ is referred toas an “inner circle”. A ratio of the radius R₂ to the radius R₁ isreferred to as a “radius ratio” (or “ring ratio”). Note that here, R₁ isa real number, R₂ is a real number, R₁ is greater than zero, and R₂ isgreater than zero. Further, R₁ is less than R₂.

Further, on the circumference of the outer circle are arranged twelveconstellation points and on the circumference of the inner circle arearranged four constellation points. The (12,4) in (12,4)16APSK indicatesthat in the order of outer circle, inner circle, there are twelve andfour constellation points, respectively.

Coordinates of each constellation point of (12,4)16APSK on the I-Q planeare as follows:

Constellation point 1-1 [0000] . . . (R₂ cos(π/4),R₂ sin(π/4))

Constellation point 1-2 [1000] . . . (R₂ cos(5π/12),R₂ sin(5π/12))

Constellation point 1-3 [1100] . . . (R₁ cos(π/4),R₁ sin(π/4))

Constellation point 1-4 [0100] . . . (R₂ cos(π/12),R₂ sin(π/12))

Constellation point 2-1 [0010] . . . (R₂ cos(3π/4),R₂ sin(3π/4))

Constellation point 2-2 [1010] . . . (R₂ cos(7π/12),R₂ sin(7π/12))

Constellation point 2-3 [1110] . . . (R₁ cos(3π/4),R₁ sin(3π/4))

Constellation point 2-4 [0110] . . . (R₂ cos(11π/12),R₂ sin(11π/12))

Constellation point 3-1 [0011] . . . (R₂ cos(−3π/4),R₂ sin(−3π/4))

Constellation point 3-2 [1011] . . . (R₂ cos(−7π/12),R₂ sin(−7π/12))

Constellation point 3-3 [1111] . . . (R₁ cos(−3π/4),R₁ sin(−3π/4))

Constellation point 3-4 [0111] . . . (R₂ cos(−11π/12),R₂ sin(−11π/12))

Constellation point 4-1 [0001] . . . (R₂ cos(−π/4),R₂ sin(−π/4))

Constellation point 4-2 [1001] . . . (R₂ cos(−5π/12),R₂ sin(−5π/12))

Constellation point 4-3 [1101] . . . (R₁ cos(−π/4),R₁ sin(−π/4))

Constellation point 4-4 [0101] . . . (R₂ cos(−π/12),R₂ sin(−π/12))

With respect to phase, the unit used is radians. Accordingly, forexample, referring to R₂ cos(π/4), the unit of π/4 is radians.Hereinafter, the unit of phase is radians.

Further, for example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (R₂ cos(π/4),R₂ sin(π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₂cos(π/4),R₂ sin(π/4)). As another example, the following relationship isdisclosed above:

Constellation point 4-4 [0101] . . . (R₂ cos(−π/12),R₂ sin(−π/12))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0101], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₂cos(−π/12),R₂ sin(−π/12)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

As illustrated in FIG. 9, constellation points of (8,8)16APSK mappingare arranged in two concentric circles having different radii (amplitudecomponents) in the I-Q plane. On the circumference of the outer circleare arranged eight constellation points and on the circumference of theinner circle are arranged eight constellation points. The (8,8) in(8,8)16APSK indicates that in the order of outer circle, inner circle,there are eight and eight constellation points, respectively. Further,as with (12,4)16APSK, among the concentric circles, the circle having alarger radius R₂ is referred to as the “outer circle” and the circlehaving a smaller radius R₁ is referred to as the “inner circle”. A ratioof the radius R₂ to the radius R₁ is referred to as a “radius ratio” (or“ring ratio”). Note that here, R₁ is a real number, R₂ is a real number,R₁ is greater than zero, and R₂ is greater than zero. Also, R₁ is lessthan R₂.

Coordinates of each constellation point of (8,8)16APSK on the I-Q planeare as follows:

Constellation point 1-1 [0000] . . . (R₁ cos(π/8),R₁ sin(π/8))

Constellation point 1-2 [0010] . . . (R₁ cos(3π/8),R₁ sin(3π/8))

Constellation point 1-3 [0110] . . . (R₁ cos(5π/8),R₁ sin(5π/8))

Constellation point 1-4 [0100] . . . (R₁ cos(7π/8),R₁ sin(7π/8))

Constellation point 1-5 [1100] . . . (R₁ cos(−7π/8),R₁ sin(−7π/8))

Constellation point 1-6 [1110] . . . (R₁ cos(−5π/8),R₁ sin(−5π/8))

Constellation point 1-7 [1010] . . . (R₁ cos(−3π/8),R₁ sin(−3π/8))

Constellation point 1-8 [1000] . . . (R₁ cos(−π/8),R₁ sin(−π/8))

Constellation point 2-1 [0001] . . . (R₂ cos(π/8),R₂ sin(π/8))

Constellation point 2-2 [0011] . . . (R₂ cos(3π/8),R₂ sin(3π/8))

Constellation point 2-3 [0111] . . . (R₂ cos(5π/8),R₂ sin(5π/8))

Constellation point 2-4 [0101] . . . (R₂ cos(7π/8),R₂ sin(7π/8))

Constellation point 2-5 [1101] . . . (R₂ cos(−7π/8),R₂ sin(−7π/8))

Constellation point 2-6 [1111] . . . (R₂ cos(−5π/8),R₂ sin(−5π/8))

Constellation point 2-7 [1011] . . . (R₂ cos(−3π/8),R₂ sin(−3π/8))

Constellation point 2-8 [1001] . . . (R₂ cos(−π/8),R₂ sin(−π/8))

For example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (R₁ cos(π/8),R₁ sin(π/8))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₁cos(π/8),R₁ sin(π/8)). As another example, the following relationship isdisclosed above:

Constellation point 2-8 [1001] . . . (R₂ cos(−π/8),R₂ sin(−π/8))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1001], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₂cos(−π/8),R₂ sin(−π/8)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 1-5, constellation point 1-6, constellation point 1-7,constellation point 1-8, constellation point 2-1, constellation point2-2, constellation point 2-3, constellation point 2-4, constellationpoint 2-5, constellation point 2-6, constellation point 2-7, andconstellation point 2-8.

<Transmission Output>

In order to achieve the same transmission output for each of the twotypes of modulation scheme above, the following normalizationcoefficient may be used.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 23} \right\rbrack & \; \\{a_{({12,4})} = \frac{z}{\sqrt{\left( {{4 \times R_{1}^{2}} + {12 \times R_{2}^{2}}} \right)/16}}} & \left( {{Math}\mspace{14mu} 23} \right) \\\left\lbrack {{Math}\mspace{14mu} 24} \right\rbrack & \; \\{a_{({8,8})} = \frac{z}{\sqrt{\left( {R_{1}^{2} + R_{2}^{2}} \right)/2}}} & \left( {{Math}\mspace{14mu} 24} \right)\end{matrix}$

Note that a_((12,4)) is a normalization coefficient of (12,4)16APSK anda_((8,8)) is a coefficient of (8,8)16APSK.

Prior to normalization, the in-phase component of a baseband signal isI_(b) and the quadrature component of the baseband signal is Q_(b).After normalization, the in-phase component of the baseband signal isI_(n) and the quadrature component of the baseband signal is Q_(n).Thus, when a modulation scheme is (12,4)16APSK, (I_(n),Q_(n))=(a_((12,4))×I_(b), a_((12,4))×Q_(b)) holds true, and when amodulation scheme is (8,8)16APSK, (I_(n), Q_(n))=(a_((8,8))×I_(b),a_((8,8))×Q_(b)) holds true.

When a modulation scheme is (12,4)16APSK, the in-phase component I_(b)and quadrature component Q_(b) are the in-phase component I andquadrature component Q, respectively, of a baseband signal after mappingthat is obtained by mapping based on FIG. 8. Accordingly, when amodulation scheme is (12,4)16APSK, the following relationships holdtrue:

-   -   Constellation point 1-1 [0000] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂ cos(π/4), a_((12,4))×R₂×sin(π/4))    -   Constellation point 1-2 [1000] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(5π/12), a_((12,4))×R₂×sin(5π/12))    -   Constellation point 1-3 [1100] . . . (I_(n),        Q_(n))=(a_((12,4))×R₁×cos(π/4), a_((12,4))×R₁×sin(π/4))    -   Constellation point 1-4 [0100] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(π/12), a_((12,4))×R₂×sin(π/12))    -   Constellation point 2-1 [0010] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(3π/4), a_((12,4))×R₂×sin(3π/4))    -   Constellation point 2-2 [1010] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(7π/12), a_((12,4))R₂×sin(7π/12))    -   Constellation point 2-3 [1110]. . . (I_(n),        Q_(n))=(a_((12,4))×R₁×cos(3π/4), a_((12,4))×R₁×sin(3π/4))    -   Constellation point 2-4 [0110] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(11π/12), a_((12,4))×R₂×sin(11π/12))    -   Constellation point 3-1 [0011] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(−3π/4), a_((12,4))R₂×sin(−3π/4))    -   Constellation point 3-2 [1011] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(−7π/12), a_((12,4))×R₂×sin(−7π/12))    -   Constellation point 3-3 [1111] . . . (I_(n),        Q_(n))=(a_((12,4))R₁×cos(−3π/4), a_((12,4))×R₂×sin(−3π/4))    -   Constellation point 3-4 [0111] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(−11π/12), a_((12,4))×R₂×sin(−11π/12))    -   Constellation point 4-1 [0001] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(−π/4), a_((12,4))R₂×sin(−7π/4))    -   Constellation point 4-2 [1001] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(−5π/12), a_((12,4))×R₂×sin(−5π/12))    -   Constellation point 4-3 [1101] . . . (I_(n),        Q_(n))=(a_((12,4))×R₁×cos(−π/4), a_((12,4))×R₁×sin(−π/4))    -   Constellation point 4-4 [0101] . . . (I_(n),        Q_(n))=(a_((12,4))×R₂×cos(−π/12), a_((12,4))×R₂×sin(−π/12))

For example, the following relationship is disclosed above:

-   -   Constellation point 1-1 [0000] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(π/4), a_((12,4))R₂×sin(π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], (I_(n), Q_(n))=(a_((12,4))R₂×cos(π/4),a_((12,4))×R₂×sin(π/4)).

As another example, the following relationship is disclosed above:

-   -   Constellation point 4-4 [0101] . . . (I_(n),        Q_(n))=(a_((12,4))R₂×cos(−π/12), a_((12,4))×R₂×sin(−π/12))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0101], (I_(n), Q_(n))=(a_((12,4)) R₂×cos(−π/12),a_((12,4))×R₂×sin(−π/12)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

Thus, the mapper 708 outputs I_(n) and Q_(n), as described above, as anin-phase component and a quadrature component, respectively, of abaseband signal.

In a similar way, when a modulation scheme is (8,8)16APSK, the in-phasecomponent I_(b) and quadrature component Q_(b) are the in-phasecomponent I and quadrature component Q, respectively, of a basebandsignal after mapping that is obtained by mapping based on FIG. 9.Accordingly, when a modulation scheme is (8,8)16APSK, the followingrelationships hold true:

-   -   Constellation point 1-1 [0000] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(π/8), a_((8,8))×R₁×sin(π/8))    -   Constellation point 1-2 [0010] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(3π/8), a_((8,8))R₁×sin(3π/8))    -   Constellation point 1-3 [0110] . . . (I_(n),        Q_(n))=(a_((8,8))R₁×cos(5π/8), a_((8,8))×R₁×sin(5π/8))    -   Constellation point 1-4 [0100] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(7π/8), a_((8,8))×R₁×sin(7π/8))    -   Constellation point 1-5 [1100] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(−7π/8), a_((8,8))×R₁×sin(−7π/8))    -   Constellation point 1-6 [1110] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(−5π/8), a_((8,8))×R₁×sin(−5π/8))    -   Constellation point 1-7 [1010] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(−3π/8), a_((8,8))×R₁×sin(−3π/8))    -   Constellation point 1-8 [1000] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(−π/8), a_((8,8))×R₁×sin(−π/8))    -   Constellation point 2-1 [0001] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(7π/8), a_((8,8))×R₂×sin(π/8))    -   Constellation point 2-2 [0011] . . . (I_(n), Q_(n))=(a_((8,8))R₂        cos(3π/8), a_((8,8))×R₂×sin(3π/8))    -   Constellation point 2-3 [0111] . . . (I_(n), Q_(n))=(a_((8,8))R₂        cos(5π/8), a_((8,8))×R₂×sin(5π/8))    -   Constellation point 2-4 [0101] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(7π/8), a_((8,8))×R₂×sin(7π/8))    -   Constellation point 2-5 [1101] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(−7π/8), a_((8,8))×R₂×sin(−7π/8))    -   Constellation point 2-6 [1111] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(−5π/8), a_((8,8))×R₂×sin(−5π/8))    -   Constellation point 2-7 [1011] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(−3π/8), a_((8,8))×R₂×sin(−3π/8))    -   Constellation point 2-8 [1001] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂ cos(−7π/8), a_((8,8))×R₂×sin(−π/8))

For example, the following relationship is disclosed above:

-   -   Constellation point 1-1 [0000] . . . (I_(n),        Q_(n))=(a_((8,8))×R₁×cos(π/8), a_((8,8))×R₁×sin(π/8))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], (I_(n), Q_(n))=(a_((8,8))×R₁×cos(π/8),a_((8,8))×R₁×sin(π/8)). As another example, the following relationshipis disclosed above:

-   -   Constellation point 2-8 [1001] . . . (I_(n),        Q_(n))=(a_((8,8))×R₂×cos(−π/8), a_((8,8))×R₂×sin(−π/8))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1001], (I_(n), Q_(n))=(a_((8,8))×R₂×cos(−π/8),a_((8,8))×R₂×sin(−π/8)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 1-5, constellation point 1-6, constellation point 1-7,constellation point 1-8, constellation point 2-1, constellation point2-2, constellation point 2-3, constellation point 2-4, constellationpoint 2-5, constellation point 2-6, constellation point 2-7, andconstellation point 2-8.

Thus, the mapper 708 outputs I_(n) and Q_(n), as described above, as anin-phase component and a quadrature component, respectively, of abaseband signal.

<Frame Configuration of Modulated Signal>

The following describes frame configuration of a modulated signal whenthe present embodiment is applied to advanced wide band digitalsatellite broadcasting.

FIG. 10 is a block diagram related to generation of a modulated signal.FIG. 11 illustrates a frame configuration of a modulated signal.

Note that the blocks related to modulated signal generation in FIG. 10are the error correction coder 702, the control information generatorand mapper 704, the interleaver 706, and the mapper 708 in FIG. 7,consolidated and re-drawn.

A transmission and multiplexing configuration control (TMCC) signal is acontrol signal for performing control related to transmission andmultiplexing such as a plurality of transmission modes (modulationscheme/error correction coding rate). Further, a TMCC signal indicatesassignment of a modulation scheme for each symbol (or slot composed froma plurality of symbols).

A selector 1001 in FIG. 10 switches contact 1 and contact 2 so thatsymbol sequences of modulated wave output are arranged as illustrated inFIG. 11. Specifically, switching is performed as follows.

During synchronous transmission: Contact 1=d, contact 2=e.

During pilot transmission: Contact 1=c, contact 2=selection from a to eaccording to modulation scheme assigned to slot (or symbol) (as animportant point of the present invention, b1 and b2 may be alternatelyselected for each symbol—this point is described in detail later).

During TMCC transmission: Contact 1=b, contact 2=e.

During data transmission: Contact 1=a, contact 2=selection from a to eaccording to modulation scheme assigned to slot (or symbol) (as animportant point of the present invention, b1 and b2 may be alternately(or regularly) selected for each symbol—this point is described indetail later).

Information for arrangement indicated in FIG. 11 is included in thecontrol signal of FIG. 10.

The interleaver 706 performs bit interleaving (bit permuting) based oninformation in the control signal.

The mapper 708 performs mapping according to a scheme selected by theselector 1001 based on the information in the control signal.

The modulator 710 performs processing such as time divisionmultiplexing/quadrature modulation and bandlimiting according to a rootroll-off filter, and outputs a modulated wave.

<Example of Data Symbol Pertaining to Present Invention>

As described above, in advanced wide band digital satellitebroadcasting, in an in-phase (I)-quadrature-phase (Q) plane,(12,4)16APSK is used as a modulation scheme that broadcasts 16constellation points, in other words four bits by one symbol. One reasonfor this is that PAPR of (12,4)16APSK is, for example, less than PAPR of16QAM and PAPR of (8,8)16APSK, and therefore average transmission powerof radio waves transmitted from a broadcast station, i.e., a satellite,can be increased. Accordingly, although BER properties of (12,4)16APSKare worse than BER properties of 16QAM and (8,8)16APSK, when the pointthat average transmission power can be set higher is considered, theprobability of achieving a wide reception area is high (this point isdescribed in more detail above).

Accordingly, in an in-phase (I)-quadrature-phase (Q) plane, as long as amodulation scheme (or transmission method) having a low PAPR and goodBER properties is used as a modulation scheme (or transmission method)having 16 constellation points, the probability of achieving a widereception area is high. The present invention is an invention based onthis point (note that “good BER properties” means that at a given SNR, alow BER is achieved).

An outline of a method of constructing a data symbol, which is one pointof the present invention, is described below.

“In a symbol group of at least three consecutive symbols (or at leastfour consecutive symbols), among which a modulation scheme for eachsymbol is (12,4)16APSK or (8,8)16APSK, there are no consecutive(12,4)16APSK symbols and there are no consecutive (8,8)16APSK symbols.”(However, as described in modifications below, there is a transmissionmethod that can obtain a similar effect to the above symbol arrangementeven as a method that does not satisfy this outline.)

This point is explained with specific examples below.

The 136 symbols of Data#7855 in FIG. 11 are, as illustrated in FIG. 11,ordered along a time axis into “1st symbol”, “2nd symbol”, “3rd symbol”,. . . , “135th symbol”, and “136th symbol”.

A (12,4)16APSK modulation scheme is used for odd-numbered symbols, andan (8,8)16APSK modulation scheme is used for even-numbered symbols.

An example of data symbols is illustrated in FIG. 12. FIG. 12illustrates six symbols among 136 symbols (from “51st symbol” to “56thsymbol”). As illustrated in FIG. 12, among consecutive symbols, twotypes of modulation scheme are alternately used in an order(12,4)16APSK, (8,8)16APSK, (12,4)16APSK, (8,8)16APSK, (12,4)16APSK,(8,8)16APSK.

FIG. 12 illustrates the following.

When four bits [b₃b₂b₁b₀] transmitted as the “51st symbol” are [1100],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(12,4)16APSK)

When four bits [b₃b₂b₁b₀] transmitted as the “52nd symbol” are [0101],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(8,8)16APSK)

When four bits [b₃b₂b₁b₀] transmitted as the “53rd symbol” are [0011],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(12,4)16APSK)

When four bits [b₃b₂b₁b₀] transmitted as the “54th symbol” are [0110],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(8,8)16APSK)

When four bits [b₃b₂b₁b₀] transmitted as the “55th symbol” are [1001],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(12,4)16APSK)

When four bits [b₃b₂b₁b₀] transmitted as the “56th symbol” are [0010],an in-phase component and quadrature component of a baseband signalcorresponding to the constellation point marked by a black circle () inFIG. 12 is transmitted by the transmit apparatus. (modulation scheme:(8,8)16APSK)

Note that in the above example an “odd-numbered symbol=(12,4)16APSK andeven-numbered symbol=(8,8)16APSK modulation scheme configuration” isdescribed, but this may be an “even-numbered symbol=(8,8)16APSK andodd-numbered symbol=(12,4)16APSK modulation scheme configuration”.

Thus, a transmission method having a low PAPR and good BER properties isachieved, and because an average transmission power can be set high andBER properties are good, the probability of achieving a wide receptionarea is high.

<Advantage of Arranging Alternate Symbols of Different ModulationSchemes>

According to the present invention, among modulation schemes having 16constellation points in an I-Q plane, and in particular (12,4)16APSK forwhich PAPR is low and (8,8)16APSK for which PAPR is slightly higher: “Ina symbol group of at least three consecutive symbols (or at least fourconsecutive symbols), among which a modulation scheme for each symbol is(12,4)16APSK or (8,8)16APSK, there are no consecutive (12,4)16APSKsymbols and there are no consecutive (8,8)16APSK symbols”.

When (8,8)16APSK symbols are arranged consecutively, PAPR becomes higheras (8,8)16APSK symbols continue. However, in order that (8,8)16APSKsymbols are not consecutive, “in a symbol group of at least threeconsecutive symbols (or at least four consecutive symbols), among whicha modulation scheme for each symbol is (12,4)16APSK or (8,8)16APSK,there are no consecutive (12,4)16APSK symbols and there are noconsecutive (8,8)16APSK symbols”, and therefore there are no consecutiveconstellation points in connection with (8,8)16APSK. Thus, PAPR isinfluenced by (12,4)16APSK, for which PAPR is low, and an effect ofsuppressing PAPR is obtained.

In connection with BER properties, when (12,4)16APSK symbols areconsecutive, BER properties are poor when performing BICM (or BICM-ID)but “in a symbol group of at least three consecutive symbols (or atleast four consecutive symbols), among which a modulation scheme foreach symbol is (12,4)16APSK or (8,8)16APSK, there are no consecutive(12,4)16APSK symbols and there are no consecutive (8,8)16APSK symbols”.Thus, BER properties are influenced by (8,8)16APSK, and an effect ofimproving BER properties is obtained.

In particular, in order to obtain the low PAPR mentioned above, settingof the ring ratio of (12,4)16APSK and the ring ratio of (8,8)16APSK isof importance.

According to R₁ and R₂ used in representing the constellation points inthe I-Q plane of (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSKrepresents R_((12,4))=R₂/R₁.

In the same way, according to R₁ and R₂ used in representing theconstellation points in the I-Q plane of (8,8)16APSK, a ring ratioR_((8,8)) of (8,8)16APSK represents R_((8,8))=R₂/R₁.

Thus, an effect is obtained that “when R_((8,8))<R_((12,4)), theprobability of further lowering PAPR is high”.

When “in a symbol group of at least three consecutive symbols (or atleast four consecutive symbols), among which a modulation scheme foreach symbol is (12,4)16APSK or (8,8)16APSK, there are no consecutive(12,4)16APSK symbols and there are no consecutive (8,8)16APSK symbols”,a modulation scheme likely to control peak power is (8,8)16APSK. Peakpower generated by (8,8)16APSK is likely to increase as R_((8,8))increases. Accordingly, in order to avoid increasing peak power, settingR_((8,8)) low is preferable. On the other hand, there is a high degreeof freedom for R_((12,4)) of (12,4)16APSK as long as a value is set forwhich BER properties are good. Thus, it is likely that the relationshipR_((8,8))<R_((12,4)) is preferable.

However, even when R_((8,8))>R_((12,4)), an effect of lowering PAPR of(8,8)16APSK can be obtained.

Accordingly, when focusing on improving BER properties,R_((8,8))>R_((12,4)) may be preferable.

The above-described relationship of ring ratios is also true for themodifications described later (<Patterns of switching modulationschemes, etc.>).

According to the embodiment described above, by alternately arrangingsymbols of different modulation schemes, PAPR is low and contribution ismade towards providing improved data reception quality.

As stated above, an outline of the present invention is: “in a symbolgroup of at least three consecutive symbols (or at least fourconsecutive symbols), among which a modulation scheme for each symbol is(12,4)16APSK or (8,8)16APSK, there are no consecutive (12,4)16APSKsymbols and there are no consecutive (8,8)16APSK symbols”. The followingdescribes labelling and constellations of (12,4)16APSK, and labellingand constellations of (8,8)16APSK for increasing the probability of areceive apparatus obtaining high data reception quality.

<Labelling and Constellations of (12,4)16APSK>

[Labelling of (12,4)16APSK]

The following describes labelling of (12,4)16APSK. Labelling is therelationship between four bits [b₃b₂b₁b₀], which are input, andarrangement of constellation points in an in-phase (I)-quadrature-phase(Q) plane. An example of labelling of (12,4)16APSK is illustrated inFIG. 8, but labelling need not conform to FIG. 8 as long as labellingsatisfies the following <Condition 1> and <Condition 2>.

For the purposes of description, the following definitions are used.

When four bits to be transmitted are [b_(a3)b_(a2)b_(a1)b_(a0)], aconstellation point A is provided in the in-phase (I)-quadrature-phase(Q) plane, and when four bits to be transmitted are[b_(b3)b_(b2)b_(b1)b_(b0)], a constellation point B is provided in thein-phase (I)-quadrature-phase (Q) plane.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as zero.

Further, the following definitions are made.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as four.

Thus, group definitions are performed.

In labelling and constellation of (12,4)16APSK in an in-phase(I)-quadrature-phase (Q) plane in FIG. 8, constellation point 1-1,constellation point 1-2, constellation point 1-3, and constellationpoint 1-4 are defined as group 1. In the same way, constellation point2-1, constellation point 2-2, constellation point 2-3, and constellationpoint 2-4 are defined as group 2; constellation point 3-1, constellationpoint 3-2, constellation point 3-3, and constellation point 3-4 aredefined as group 3; and constellation point 4-1, constellation point4-2, constellation point 4-3, and constellation point 4-4 are defined asgroup 4.

The following two conditions are provided.

<Condition 1>

X represents 1, 2, 3, and 4. All values of X satisfy the following:

The number of different bits of labelling between constellation pointX-1 and constellation point X-2 is one;

The number of different bits of labelling between constellation pointX-2 and constellation point X-3 is one;

The number of different bits of labelling between constellation pointX-3 and constellation point X-4 is one; and

The number of different bits of labelling between constellation pointX-4 and constellation point X-1 is one.

<Condition 2>

In the outer circle:

The number of different bits of labelling between constellation point1-2 and constellation point 2-2 is one;

The number of different bits of labelling between constellation point3-2 and constellation point 4-2 is one;

The number of different bits of labelling between constellation point1-4 and constellation point 4-4 is one; and

The number of different bits of labelling between constellation point2-4 and constellation point 3-4 is one.

In the inner circle:

The number of different bits of labelling between constellation point1-3 and constellation point 2-3 is one;

The number of different bits of labelling between constellation point2-3 and constellation point 3-3 is one;

The number of different bits of labelling between constellation point3-3 and constellation point 4-3 is one; and

The number of different bits of labelling between constellation point4-3 and constellation point 1-3 is one.

By satisfying the above conditions, the number of different bits oflabelling among constellation points that are near each other in anin-phase (I)-quadrature-phase (Q) plane is low, and therefore thepossibility of a receive apparatus achieving high data reception qualityis increased. Thus, when a receive apparatus performs iterativedetection, the possibility of the receive apparatus achieving high datareception quality is increased.

Constellation of (12,4)16APSK

The above describes constellation and labelling in an in-phase(I)-quadrature-phase (Q) plane of FIG. 14, but constellation andlabelling in an in-phase (I)-quadrature-phase (Q) plane is not limitedto this example. For example, labelling of coordinates on an I-Q planeof each constellation point of (12,4)16APSK may be performed as follows.

Coordinates on an I-Q plane of the constellation point 1-1: (cosθ×R₂×cos(π/4)−sin θ×R₂×sin(π/4), sin θ×R₂×cos(π/4)+cos θ×R₂×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-2: (cosθ×R₂×cos(5π/12)−sin θ×R₂×Sin(5π/12), sin θ×R₂×cos(5π/12)+cosθ×R₂×sin(5π/12))

Coordinates on an I-Q plane of the constellation point 1-3: (cosθ×R₁×cos(π/4)−sin θ×R₁×sin(π/4), sin θ×R₁×cos(π/4)+cos θ×R₁×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-4: (cos θ×R₂cos(π/12)−sin θ×R₂×sin(π/12), sin θ×R₂ cos(π/12)+cos θ×R₂×sin(π/12))

Coordinates on an I-Q plane of the constellation point 2-1: (cosθ×R₂×cos(3π/4)−sin θ×R₂×sin(3π/4), sin θ×R₂ cos(3π/4)+cosθ×R₂×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 2-2: (cos θ×R₂cos(7π/12)−sin θ×R₂×sin(7π/12), sin θ×R₂×cos(7π/12)+cos θ×R₂×sin(7π/12))

Coordinates on an I-Q plane of the constellation point 2-3: (cosθ×R₁×cos(3π/4)−sin θ×R₁×sin(3π/4), sin θ×R₁×cos(3π/4)+cosθ×R₁×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 2-4: (cosθ×R₂×cos(11π/12)−sin θ×R₂×sin(11π/12), sin θ×R₂ cos(11π/12)+cosθ×R₂×sin(11π/12))

Coordinates on an I-Q plane of the constellation point 3-1: (cosθ×R₂×cos(−3π/4)−sin θ×R₂×sin(−3π/4), sin θ×R₂×cos(−3π/4)+cosθλR₂×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-2: (cosθ×R₂×cos(−7π/12)−sin θ×R₂×Sin(−7π/12), sin θ×R₂×cos(−7π/12)+cosθ×R₂×sin(−7π/12))

Coordinates on an I-Q plane of the constellation point 3-3: (cosθ×R₁×cos(−3π/4)−sin θ×R₁×sin(−3π/4), sin θ×R₁×cos(−3π/4)+cosθ×R₁×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-4: (cosθ×R₂×cos(−11π/12)−sin θ×R₂×sin(−11π/12), sin θ×R₂×cos(−11π/12)+cosθ×R₂×sin(−11π/12))

Coordinates on an I-Q plane of the constellation point 4-1: (cosθ×R₂×cos(−π/4)−sin θ×R₂×sin(−π/4), sin θ×R₂×cos(−π/4)+cosθ×R₂×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 4-2: (cosθ×R₂×cos(−5π/12)−sin θ×R₂×sin(−5π/12), sin θ×R₂×cos(−5π/12)+cosθ×R₂×sin(−5π/12))

Coordinates on an I-Q plane of the constellation point 4-3: (cosθ×R₁×cos(−π/4)−sin θ×R₁×sin(−π/4), sin θ×R₁×cos(−π/4)+cosθ×R₁×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 4-4: (cosθ×R₂×cos(−π/12)−sin θ×R₂×sin(−π/12), sin θ×R₂×cos(−π/12)+cosθ×R₂×sin(−π/12))

With respect to phase, the unit used is radians. Accordingly, anin-phase component I_(n) and a quadrature component Q_(n) of a basebandsignal after normalization is represented as below.

Coordinates on an I-Q plane of the constellation point 1-1: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(π/4)−a_((12,4))×sin θ×R₂×sin(π/4),a_((12,4))×sin θ×R₂ cos(π/4)+a_((12,4))×cos θ×R₂×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-2: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(5π/12)−a_((12,4))×sin θ×R₂×sin(5π/12),a_((12,4))×sin θ×R₂×cos(5π/12)+a_((12,4))×cos θ×R₂×sin(5π/12))

Coordinates on an I-Q plane of the constellation point 1-3: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₁×cos(π/4)−a_((12,4))×sin θ×R₁×sin(π/4),a_((12,4))×sin θ×R₁×cos(π/4)+a_((12,4))×cos θ×R₁×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-4: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(π/12)−a_((12,4))×sin θ×R₂×sin(π/12),a_((12,4))×sin θ×R₂×cos(π/12)+a_((12,4))×cos θ×R₂×sin(π/12))

Coordinates on an I-Q plane of the constellation point 2-1: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(3π/4)−a_((12,4))×sin θ×R₂×sin(3π/4),a_((12,4))×sin θ×R₂×cos(3π/4)+a_((12,4))×cos θ×R₂×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 2-2: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(7π/12)−a_((12,4))×sin θ×R₂×sin(7π/12),a_((12,4))×sin θ×R₂×cos(7π/12)+a_((12,4))×cos θ×R₂×sin(7π/12))

Coordinates on an I-Q plane of the constellation point 2-3: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₁×cos(3π/4)−a_((12,4))×sin θ×R₁×sin(3π/4),a_((12,4))×sin θ×R₁×cos(3π/4)+a_((12,4))×cos θ×R₁×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 2-4: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(11π/12)−a_((12,4))×sin θ×R₂×sin(11π/12),a_((12,4))×sin θ×R₂×cos(11π/12)+a_((12,4))×cos θ×R₂×sin(11π/12))

Coordinates on an I-Q plane of the constellation point 3-1: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−3π/4)−a_((12,4))×sin θ×R₂×sin(−3π/4),a_((12,4))×sin θ×R₂×cos(−3π/4)+a_((12,4))×cos θ×R₂×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-2: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−7π/12)−a_((12,4))×sin θ×R₂×sin(−7π/12),a_((12,4))×sin θ×R₂×cos(−7π/12)+a_((12,4))×cos θ×R₂×sin(−7π/12))

Coordinates on an I-Q plane of the constellation point 3-3: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₁×cos(−3π/4)−a_((12,4))×sin θ×R₁×sin(−3π/4),a_((12,4))×sin θ×R₁×cos(−3π/4)+a_((12,4))×cos θ×R₁×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-4: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−11π/12)−a_((12,4))×sinθ×R₂×sin(−11π/12), a_((12,4))×sin θ×R₂ cos(−11π/12)+a_((12,4))×cosθ×R₂×sin(−11π/12))

Coordinates on an I-Q plane of the constellation point 4-1: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−π/4)−a_((12,4)) sin θ×R₂×sin(−π/4),a_((12,4))×sin θ×R₂×cos(−π/4)+a_((12,4))×cos θ×R₂×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 4-2: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−5π/12)−a_((12,4))×sin θ×R₂×sin(−5π/12),a_((12,4)) sin θ×R₂×cos(−5π/12)+a_((12,4))×cos θ×R₂×sin(−5π/12))

Coordinates on an I-Q plane of the constellation point 4-3: (I_(n),Q_(n))=(a_((12,4))×cos R₁×cos(−π/4)−a_((12,4))×sin θ×R₁×sin(−π/4),a_((12,4))×sin θ×R₁×cos(−π/4)+a_((12,4))×cos θ×R₁×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 4-4: (I_(n),Q_(n))=(a_((12,4))×cos θ×R₂×cos(−π/12)−a_((12,4))×sin θ×R₂×sin(−π/12),a_((12,4))×sin θ×R₂×cos(−π/12)+a_((12,4))×cos θ×R₂×sin(−π/12))

Note that θ is a phase provided on an in-phase (I)-quadrature-phase (Q)plane, and a_((12,4)) is as shown in Math (23).

In a scheme wherein “in a symbol group of at least three consecutivesymbols (or at least four consecutive symbols), among which a modulationscheme for each symbol is (12,4)16APSK or (8,8)16APSK, there are noconsecutive (12,4)16APSK symbols and there are no consecutive(8,8)16APSK symbols”, a (12,4)16APSK modulation scheme may be used forwhich coordinates on an I-Q plane of each constellation point are asdescribed above and <Condition 1> and <Condition 2> are satisfied.

One example that satisfies the above is an example of constellation andlabelling of (12,4)16APSK illustrated in FIG. 15. FIG. 15 shows everyconstellation point rotated π/6 radians with respect to FIG. 14, so thatθ=π/6.

<Labelling and Constellations of (8,8)16APSK>

[Labelling of (8,8)16APSK]

The following describes labelling of (8,8)16APSK. An example oflabelling of (8,8)16APSK is illustrated in FIG. 9, but labelling neednot conform to FIG. 9 as long as labelling satisfies the following<Condition 3> and <Condition 4>.

For the purposes of description, the following definitions are used.

As illustrated in FIG. 16, eight constellation points on thecircumference of the inner circle are defined as group 1: constellationpoint 1-1, constellation point 1-2, constellation point 1-3,constellation point 1-4, constellation point 1-5, constellation point1-6, constellation point 1-7, and constellation point 1-8. Further,eight constellation points on the circumference of the outer circle aredefined as group 2: constellation point 2-1, constellation point 2-2,constellation point 2-3, constellation point 2-4, constellation point2-5, constellation point 2-6, constellation point 2-7, and constellationpoint 2-8.

The following two conditions are provided.

<Condition 3>

X represents 1 and 2. All values of X satisfy the following:

The number of different bits of labelling between constellation pointX-1 and constellation point X-2 is one.

The number of different bits of labelling between constellation pointX-2 and constellation point X-3 is one.

The number of different bits of labelling between constellation pointX-3 and constellation point X-4 is one.

The number of different bits of labelling between constellation pointX-4 and constellation point X-5 is one.

The number of different bits of labelling between constellation pointX-5 and constellation point X-6 is one.

The number of different bits of labelling between constellation pointX-6 and constellation point X-7 is one.

The number of different bits of labelling between constellation pointX-7 and constellation point X-8 is one.

The number of different bits of labelling between constellation pointX-8 and constellation point X-1 is one.

Definitions of the number of different bits of labelling are asdescribed above.

<Condition 4>

Z represents 1, 2, 3, 4, 5, 6, 7, and 8. All values of Z satisfy thefollowing:

The number of different bits of labelling between constellation point1-Z and constellation point 2-Z is one.

By satisfying the above conditions, the number of different bits oflabelling among constellation points that are near each other in anin-phase (I)-quadrature-phase (Q) plane is low, and therefore thepossibility of a receive apparatus achieving high data reception qualityis increased. Thus, when a receive apparatus performs iterativedetection, the possibility of the receive apparatus achieving high datareception quality is increased.

Constellation of (8,8)16APSK

The above describes constellation and labelling in an in-phase(I)-quadrature-phase (Q) plane of FIG. 16, but constellation andlabelling in an in-phase (I)-quadrature-phase (Q) plane is not limitedto this example. For example, coordinates on an I-Q plane of eachconstellation point of (8,8)16APSK may be labelled as follows.

Coordinates on an I-Q plane of the constellation point 1-1: (cosθ×R₁×cos(π/8)−sin θ×R₁×sin(π/8), sin θ×R₁×cos(π/8)+cos θ×R₁×sin(π/8))

Coordinates on an I-Q plane of the constellation point 1-2: (cosθ×R₁×cos(3π/8)−sin θ×R₁×sin(3π/8), sin θ×R₁×cos(3π/8)+cosθ×R₁×sin(3π/8))

Coordinates on an I-Q plane of the constellation point 1-3: (cosθ×R₁×cos(5π/8)−sin θ×R₁×sin(5π/8), sin θ×R₁×cos(5π/8)+cosθ×R₁×sin(5π/8))

Coordinates on an I-Q plane of the constellation point 1-4: (cosθ×R₁×cos(7π/8)−sin θ×R₁×sin(7π/8), sin θ×R₁×cos(7π/8)+cosθ×R₁×sin(7π/8))

Coordinates on an I-Q plane of the constellation point 1-5: (cosθ×R₁×cos(−7π/8)−sin θ×R₁×sin(−7π/8), sin θ×R₁×cos(−7π/8)+cosθ×R₁×sin(−7π/8))

Coordinates on an I-Q plane of the constellation point 1-6: (cosθ×R₁×cos(−5π/8)−sin θ×R₁×sin(−5π/8), sin θ×R₁×cos(−5π/8)+cosθ×R₁×sin(−5π/8))

Coordinates on an I-Q plane of the constellation point 1-7: (cosθ×R₁×cos(−3π/8)−sin θ×R₁×sin(−3π/8), sin θ×R₁×cos(−3π/8)+cosθ×R₁×sin(−3π/8))

Coordinates on an I-Q plane of the constellation point 1-8: (cosθ×R₁×cos(−π/8)−sin θ×R₁×sin(−π/8), sin θ×R₁×cos(−π/8)+cos θ×R₁×sin(−π/8)

Coordinates on an I-Q plane of the constellation point 2-1: (cosθ×R₂×cos(π/8)−sin θ×R₁×sin(π/8), sin θ×R₂×cos(π/8)+cos θ×R₂×sin(π/8))

Coordinates on an I-Q plane of the constellation point 2-2: (cosθ×R₂×cos(3π/8)−sin θ×R₂×sin(3π/8), sin θ×R₂×cos(3π/8)+cosθ×R₂×sin(3π/8))

Coordinates on an I-Q plane of the constellation point 2-3: (cosθ×R₂×cos(5π/8)−sin θ×R₂×sin(5π/8), sin θ×R₂×cos(5π/8)+cosθ×R₂×sin(5π/8))

Coordinates on an I-Q plane of the constellation point 2-4: (cosθ×R₂×cos(7π/8)−sin θ×R₂×sin(7π/8), sin θ×R₂×cos(7π/8)+cosθ×R₂×sin(7π/8))

Coordinates on an I-Q plane of the constellation point 2-5: (cosθ×R₂×cos(−7π/8)−sin θ×R₂×sin(−7π/8), sin θ×R₂×cos(−7π/8)+cosθ×R₂×sin(−7π/8))

Coordinates on an I-Q plane of the constellation point 2-6: (cosθ×R₂×cos(−5π/8)−sin θ×R₂×sin(−5π/8), sin θ×R₂×cos(−5π/8)+cosθ×R₂×sin(−5π/8))

Coordinates on an I-Q plane of the constellation point 2-7: (cosθ×R₂×cos(−3π/8)−sin θ×R₂×sin(−3π/8), sin θ×R₂×cos(−3π/8)+cosθ×R₂×sin(−3π/8))

Coordinates on an I-Q plane of the constellation point 2-8: (cosθ×R₂×cos(−π/8)−sin θ×R₂×sin(−π/8), sin θ×R₂×cos(−π/8)+cosθ×R₂×sin(−π/8))

With respect to phase, the unit used is radians. Accordingly, anin-phase component I_(n) and a quadrature component Q_(n) of a basebandsignal after normalization is represented as below.

Coordinates on an I-Q plane of the constellation point 1-1: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₁×cos(π/8)−a_((8,8)) sin θ×R₁×sin(π/8),a_((8,8))×sin θ×R₁×cos(π/8)+a_((8,8))×cos θ×R₁×sin(π/8))

Coordinates on an I-Q plane of the constellation point 1-2: (I_(n),Q_(n))=(a_((8,8))×cos R₁×cos(3π/8)−a_((8,8))×sin θ×R₁×sin(3π/8),a_((8,8))×sin θ×R₁×cos(3π/8)+a_((8,8))×cos θ×R₁×sin(3π/8))

Coordinates on an I-Q plane of the constellation point 1-3: (I_(n),Q_(n))=(a_((8,8))×cos R₁×cos(5π/8)−a_((8,8))×sin θ×R₁×sin(5π/8),a_((8,8))×sin θ×R₁×cos(5π/8)+a_((8,8))×cos θ×R₁×sin(5π/8))

Coordinates on an I-Q plane of the constellation point 1-4: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₁×cos(7π/8)−a_((8,8))×sin θ×R₁×sin(7π/8),a_((8,8))×sin θ×R₁×cos(7π/8)+a_((8,8))×cos θ×R₁×sin(7π/8))

Coordinates on an I-Q plane of the constellation point 1-5: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₁×cos(−7π/8)−a_((8,8))×sin θ×R₁×sin(−7π/8),a_((8,8))×sin θ×R₁×cos(−7π/8)+a_((8,8))×cos θ×R₁ sin(−7π/8))

Coordinates on an I-Q plane of the constellation point 1-6: (I_(n),Q_(n))=(a_((8,8)) cos θ×R₁×cos(−5π/8)−a_((8,8))×sin θ×R₁×sin(−5π/8),a_((8,8))×sin θ×R₁×cos(−5π/8)+a_((8,8))×cos θ×R₁×sin(−5π/8))

Coordinates on an I-Q plane of the constellation point 1-7: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₁×cos(−3π/8)−a_((8,8))×sin θ×R₁×sin(−3π/8),a_((8,8))×sin θ×R₁×cos(−3π/8)+a_((8,8))×cos θ×R₁×sin(−3π/8))

Coordinates on an I-Q plane of the constellation point 1-8: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₁×cos(−π/8)−a_((8,8))×sin θ×R₁×sin(−π/8),a_((8,8))×sin θ×R₁×cos(−π/8)+a_((8,8))×cos θ×R₁×sin(−π/8))

Coordinates on an I-Q plane of the constellation point 2-1: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(π/8)−a_((8,8)) sin θ×R₂×sin(π/8),a_((8,8))×sin θ×R₂×cos(π/8)+a_((8,8))×cos θ×R₂×sin(π/8))

Coordinates on an I-Q plane of the constellation point 2-2: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(3π/8)−a_((8,8))×sin θ×R₂×sin(3π/8),a_((8,8))×sin θ×R₂×cos(3π/8)+a_((8,8))×cos θ×R₂×sin(3π/8))

Coordinates on an I-Q plane of the constellation point 2-3: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(5π/8)−a_((8,8))×sin θ×R₂×sin(5π/8),a_((8,8))×sin θ×R₂×cos(5π/8)+a_((8,8))×cos θ×R₂×sin(5π/8))

Coordinates on an I-Q plane of the constellation point 2-4: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(7π/8)−a_((8,8))×sin θ×R₂×sin(7π/8),a_((8,8))×sin θ×R₂×cos(7π/8)+a_((8,8))×cos θ×R₂×sin(7π/8))

Coordinates on an I-Q plane of the constellation point 2-5: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(−7π/8)−a_((8,8))×sin θ×R₂×sin(−7π/8),a_((8,8))×sin θ×R₂×cos(−7π/8)+a_((8,8))×cos θR₂×sin(−7π/8))

Coordinates on an I-Q plane of the constellation point 2-6: (I_(n),Q_(n))=(a_((8,8)) cos R₂×cos(−5π/8)−a_((8,8))×sin θ×R₂×sin(−5π/8),a_((8,8))×sin θ×R₂×cos(−5π/8)+a_((8,8))×cos θ×R₂×sin(−5π/8))

Coordinates on an I-Q plane of the constellation point 2-7: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(−3π/8)−a_((8,8))×sin θ×R₂×sin(−3π/8),a_((8,8))×sin θ×R₂×cos(−3π/8)+a_((8,8))×cos θ×R₂×sin(−3π/8))

Coordinates on an I-Q plane of the constellation point 2-8: (I_(n),Q_(n))=(a_((8,8))×cos θ×R₂×cos(−π/8)−a_((8,8))×sin θ×R₂×sin(−π/8),a_((8,8))×sin θ×R₂×cos(−π/8)+a_((8,8))×cos θ×R₂×sin(−π/8))

Note that θ is a phase provided on an in-phase (I)-quadrature-phase (Q)plane, and a_((8,8)) is as shown in Math (24).

In a scheme wherein “in a symbol group of at least three consecutivesymbols (or at least four consecutive symbols), among which a modulationscheme for each symbol is (12,4)16APSK or (8,8)16APSK, there are noconsecutive (12,4)16APSK symbols and there are no consecutive(8,8)16APSK symbols”, an (8,8)16APSK modulation scheme may be used forwhich coordinates on an I-Q plane of each constellation point are asdescribed above and <Condition 3> and <Condition 4> are satisfied.

Further, in a scheme wherein “in a symbol group of at least threeconsecutive symbols (or at least four consecutive symbols), among whicha modulation scheme for each symbol is (12,4)16APSK or (8,8)16APSK,there are no consecutive (12,4)16APSK symbols and there are noconsecutive (8,8)16APSK symbols”, according to the above description,when θ of (12,4)16APSK is θ=(N×π)/2 radians (N being an integer) and θof (8,8)16APSK is θ=π/8+(N×π)/4 radians (N being an integer), there is apossibility that PAPR becomes lower. FIG. 17 is an example ofconstellation and labelling when θ=π/8 radians.

<Patterns of Switching Modulation Schemes, Etc.>

In the example of FIG. 12, an example is described in which (12,4)16APSKsymbols and (8,8)16APSK symbols are alternately switched (there are noconsecutive (12,4)16APSK symbols or consecutive (8,8)16APSK symbols).The following describes modifications of the above scheme.

FIG. 23 and FIG. 24 are related to modifications.

Features of the modifications are as follows.

-   -   One period (cycle) is composed of M symbols. Note that for the        following description, one period (cycle) of M symbols is        referred to (defined as) a “symbol group of period (cycle) M”.        The following description references FIG. 23.    -   When the number of consecutive symbols is at least M+1, a        plurality of a “symbol group of period (cycle) M” is arranged.        This point is described with reference to FIG. 24.

FIG. 23 illustrates examples of symbol groups when a “symbol group ofperiod (cycle) M=5”. Features of FIG. 23 satisfy the following twopoints.

-   -   In a “symbol group of period (cycle) M=5”, the number of        (8,8)16APSK symbols is one greater than the number of        (12,4)16APSK symbols, in other words the number of (12,4)16APSK        symbols is two and the number of (8,8)16APSK symbols is three.    -   In a “symbol group of period (cycle) M=5”, there are no        consecutive (8,8)16APSK symbols or there is only 1 position at        which two consecutive (8,8)16APSK symbols exist. Accordingly,        there are no cases of three or more consecutive (8,8)16APSK        symbols.

Cases that satisfy the above two points, as methods of configuring a“symbol group of period (cycle) M=5”, are illustrated in parts (a), (b),(c), (d), and (e) of FIG. 23. In FIG. 23, the horizontal axis is time.

According to FIG. 23, part (a), when configuring a “symbol group ofperiod (cycle) M=5”, a “symbol group of period (cycle) M=5” is anarrangement of symbols in the order (8,8)16APSK symbol, (12,4)16APSKsymbol, (8,8)16APSK symbol, (12,4)16APSK symbol, and (8,8)16APSK symbol.Thus, a “symbol group of period (cycle) M=5” configured in this way isarranged in a repeating pattern.

According to FIG. 23, part (b), when configuring a “symbol group ofperiod (cycle) M=5”, a “symbol group of period (cycle) M=5” is anarrangement of symbols in the order (12,4)16APSK symbol, (8,8)16APSKsymbol, (12,4)16APSK symbol, (8,8)16APSK symbol, and (8,8)16APSK symbol.Thus, a “symbol group of period (cycle) M=5” configured in this way isarranged in a repeating pattern.

According to FIG. 23, part (c), when configuring a “symbol group ofperiod (cycle) M=5”, a “symbol group of period (cycle) M=5” is anarrangement of symbols in the order (8,8)16APSK symbol, (12,4)16APSKsymbol, (8,8)16APSK symbol, (8,8)16APSK symbol, and (12,4)16APSK symbol.Thus, a “symbol group of period (cycle) M=5” configured in this way isarranged in a repeating pattern.

According to FIG. 23, part (d), when configuring a “symbol group ofperiod (cycle) M=5”, a “symbol group of period (cycle) M=5” is anarrangement of symbols in the order (12,4)16APSK symbol, (8,8)16APSKsymbol, (8,8)16APSK symbol, (12,4)16APSK symbol, and (8,8)16APSK symbol.Thus, a “symbol group of period (cycle) M=5” configured in this way isarranged in a repeating pattern.

According to FIG. 23, part (e), when configuring a “symbol group ofperiod (cycle) M=5”, a “symbol group of period (cycle) M=5” is anarrangement of symbols in the order (8,8)16APSK symbol, (8,8)16APSKsymbol, (12,4)16APSK symbol, (8,8)16APSK symbol, and (12,4)16APSKsymbol. Thus, a “symbol group of period (cycle) M=5” configured in thisway is arranged in a repeating pattern.

Note that methods of configuring a “symbol group of period (cycle) M=5”are described with reference to FIG. 23, but the period (cycle) M is notlimited to a value of five, and the following configurations arepossible.

-   -   In a “symbol group of period (cycle) M”, the number of        (8,8)16APSK symbols is one greater than the number of        (12,4)16APSK symbols, in other words the number of (12,4)16APSK        symbols is N and the number of (8,8)16APSK symbols is N+1. Note        that N is a natural number.    -   In a “symbol group of period (cycle) M”, there are no        consecutive (8,8)16APSK symbols or there is only 1 position at        which two consecutive (8,8)16APSK symbols exist. Accordingly,        there are no cases of three or more consecutive (8,8)16APSK        symbols.

Accordingly, the period (cycle) M of a “symbol group of period (cycle)M” is an odd number greater than or equal to three, but when consideringan increase of PAPR when a modulation scheme is (12,4)16APSK a period(cycle) M of greater than or equal to five is suitable. However, evenwhen a period (cycle) M is three, there is the advantage that PAPR isless than PAPR of (8,8)16APSK.

The above describes configurations according to a “symbol group ofperiod (cycle) M”, but a periodic (cyclic) configuration need not beadopted when the following is true.

-   -   When each data symbol is either a (12,4)16APSK symbol or an        (8,8)16APSK symbol, three or more consecutive (8,8)16APSK        symbols are not present in a consecutive data symbol group.

When constellations, labelling, and ring ratios of (12,4)16APSK and(8,8)16APSK are as described above and the condition described above issatisfied, a similar effect can be obtained.

In a case as described above, two consecutive (8,8)16APSK symbols mayoccur, but an effect of a lower PAPR than PAPR of (8,8)16APSK isachieved and an effect of improving data reception quality according to(12,4)16APSK is achieved.

The following is a supplemental description, referencing FIG. 24, of amethod of configuring consecutive symbols composed of (12,4)16APSKsymbols and (8,8)16APSK symbols when other symbols are inserted.

In FIG. 24, part (a), 2400, 2409 indicate other symbol groups (here, asymbol group may indicate consecutive symbols and may indicate a singlesymbol). These other symbol groups may indicate a control symbol fortransmission of a transmission method such as a modulation scheme, anerror correction coding scheme, etc., pilot symbols or reference symbolfor a receive apparatus to perform channel estimation, frequencysynchronization, and time synchronization, or a data symbol modulated bya modulation scheme other than (12,4)16APSK or (8,8)16APSK. In otherwords, the other symbol groups are symbols for which a modulation schemeis a modulation scheme other than (12,4)16APSK or (8,8)16APSK.

In FIG. 24, part (a), 2401, 2404, 2407, and 2410 indicate a first symbolof a “symbol group of period (cycle) M” (in a “symbol group of period(cycle) f”, a first symbol of the period (cycle)). 2403, 2406, and 2412indicate a last symbol of a “symbol group of period (cycle) M” (in a“symbol group of period (cycle) M”, a last symbol of the period(cycle)).

2402, 2405, 2408, and 2411 indicate a mid symbol group of a “symbolgroup of period (cycle) M” (in a “symbol group of period (cycle) M”, asymbol group excluding the first symbol and the last symbol).

FIG. 24, part (a), illustrates an example of symbol arrangement along ahorizontal axis of time. In FIG. 24, part (a), a first symbol 2401 of a“symbol group of period (cycle) M” is arranged immediately after the“other symbol group” 2400. Subsequently, a mid symbol group 2402 of the“symbol group of period (cycle) M” and a last symbol 2403 of the “symbolgroup of period (cycle) M” are arranged. Accordingly, a “first symbolgroup of period (cycle) M” is arranged immediately after the “othersymbol group” 2400.

A “second symbol group of period (cycle) M” is arranged immediatelyafter the “first symbol group of period (cycle) M”, the “second symbolgroup of period (cycle) M” being composed of a first symbol 2404, a midsymbol group 2045, and a last symbol 2406.

A first symbol 2407 of a “symbol group of period (cycle) M” is arrangedafter the “second symbol group of period (cycle) M”, and a portion 2408of a mid symbol group of the “symbol group of period (cycle) M” isarranged subsequently.

The “other symbol group” 2409 is arranged after the portion 2408 of themid symbol group of the “symbol group of period (cycle) M”.

A feature illustrated in FIG. 24, part (a), is that a “symbol group ofperiod (cycle) M” is arranged after the “other symbol group” 2409, the“symbol group of period (cycle) M” being composed of a first symbol2410, a mid symbol group 2411, and a last symbol 2412.

FIG. 24, part (b), illustrates an example of symbol arrangement along ahorizontal axis of time. In FIG. 24, part (b), the first symbol 2401 ofa “symbol group of period (cycle) M” is arranged immediately after the“other symbol group” 2400. Subsequently, the mid symbol group 2402 ofthe “symbol group of period (cycle) M” and the last symbol 2403 of the“symbol group of period (cycle) M” are arranged. Accordingly, the “firstsymbol group of period (cycle) M” is arranged immediately after the“other symbol group” 2400.

The “second symbol group of period (cycle) M” is arranged immediatelyafter the “first symbol group of period (cycle) M”, the “second symbolgroup of period (cycle) M” being composed of the first symbol 2404, themid symbol group 2045, and the last symbol 2406.

The first symbol 2407 of the “symbol group of period (cycle) M” isarranged after the “second symbol group of period (cycle) M”, and aportion 2408 of the mid symbol group of the “symbol group of period(cycle) M” is arranged subsequently.

The “other symbol group” 2409 is arranged after the portion 2408 of themid symbol group of the “symbol group of period (cycle) M”.

A feature illustrated in FIG. 24, part (b) is that a remaining portion2408-2 of the mid symbol group of the “symbol group of period (cycle) M”is arranged after the “other symbol group” 2409, and a last symbol 2413of the “symbol group of period (cycle) M” is arranged subsequent to theremaining portion 2408. Note that a “symbol group of period (cycle) M”is formed by the first symbol 2407, the portion 2408 of the mid symbolgroup, the remaining portion 2408-2 of the mid symbol group, and thelast symbol 2413.

A “symbol group of period (cycle) M” is arranged after the last symbol2413, the “symbol group of period (cycle) M” being composed of a firstsymbol 2414, a mid symbol group 2415, and a last symbol 2416.

In FIG. 24, each “symbol group of period (cycle) M” may have the sameconfiguration as the “symbol group of period (cycle) M” described as anexample with reference to FIG. 23, and may be configured so that “in asymbol group of at least three consecutive symbols (or at least fourconsecutive symbols), among which a modulation scheme for each symbol is(12,4)16APSK or (8,8)16APSK, there are no consecutive (12,4)16APSKsymbols and there are no consecutive (8,8)16APSK symbols”.

When constellations, labelling, and ring ratios of (12,4)16APSK and(8,8)16APSK are as described above and the conditions described aboveare satisfied, a similar effect can be obtained.

According to the examples described so far, 16APSK is an example of amodulation scheme used in switching, but 32APSK and 64APSK may beimplemented in the same way.

A method of configuring consecutive symbols is as described above:

-   -   A “symbol group of period (cycle) M” is configured from a symbol        of a first modulation scheme of a first constellation in an        in-phase (I)-quadrature-phase (Q) plane and a symbol of a second        modulation scheme of a second constellation in an in-phase        (I)-quadrature-phase (Q) plane. (However, the number of        constellation points in the in-phase (I)-quadrature-phase (Q)        plane of the first modulation scheme and the number of        constellation points in the in-phase (I)-quadrature-phase (Q)        plane of the second modulation scheme are equal.)    -   In a symbol group of at least three consecutive symbols (or at        least four consecutive symbols), among which a modulation scheme        for each symbol is the first modulation scheme or the second        modulation scheme, there are no consecutive first modulation        scheme symbols and there are no consecutive second modulation        scheme symbols. (However, the number of constellation points in        the in-phase (I)-quadrature-phase (Q) plane of the first        modulation scheme and the number of constellation points in the        in-phase (I)-quadrature-phase (Q) plane of the second modulation        scheme are equal.)

FIG. 25 illustrates constellations in an in-phase (I)-quadrature-phase(Q) plane of a scheme of types of 32APSK having 32 constellation pointsin an in-phase (I)-quadrature-phase (Q) plane, according to the methoddescribed above of configuring two types of symbol as consecutivesymbols.

FIG. 25, part (a) illustrates a constellation in an in-phase(I)-quadrature-phase (Q) plane of (4,12,16)32APSK. With an originthereof as a center, constellation points a=4 exist on a circle ofradius R₁, constellation points b=12 exist on a circle of radius R₂, andconstellation points c=16 exist on a circle of radius R₃. Accordingly(a,b,c)=(4,12,16) and is therefore referred to as (4,12,16)32APSK (notethat R₁<R₂<R₃).

FIG. 25, part (b) illustrates a constellation in an in-phase(I)-quadrature-phase (Q) plane of (8,8,16)32APSK. With an origin thereofas a center, constellation points a=8 exist on a circle of radius R₁,constellation points b=8 exist on a circle of radius R₂, andconstellation points c=16 exist on a circle of radius R₃. Accordingly(a,b,c)=(8,8,16) and is therefore referred to as (8,8,16)32APSK (notethat R₁<R₂<R₃).

Thus, the method of configuring two types of symbol as consecutivesymbols described above may be implemented by (4,12,16)32APSK in FIG.25, part (a), and (8,8,16)32APSK in FIG. 25, part (b). In other words,in the method of configuring two types of symbol as consecutive symbolsdescribed above, the first modulation scheme and the second modulationscheme may be (4,12,16)32APSK and (8,8,16)32APSK, respectively.

Further, with an origin thereof as a center, constellation points a=16may exist on a circle of radius R₁ and constellation points b=16 mayexist on a circle of radius R₂, (a,b)=(16,16), thereby describing(16,16)32APSK (note that R₁<R₂).

Thus, the method of configuring two types of symbol as consecutivesymbols described above may be implemented by (4,12,16)32APSK in FIG.25, part (a), and (16,16)32APSK. In other words, in the method ofconfiguring two types of symbol as consecutive symbols described above,the first modulation scheme and the second modulation scheme may be(4,12,16)32APSK and (16,16)32APSK, respectively.

In addition a γ scheme 32APSK may be considered that has a differentconstellation to (4,12,16)32APSK, (8,8,16)32APSK, and (16,16)32APSK.Thus, the method of configuring two types of symbol as consecutivesymbols described above may be implemented by (4,12,16)32APSK in FIG.25, part (a), and the γ scheme 32APSK. In other words, in the method ofconfiguring two types of symbol as consecutive symbols described above,the first modulation scheme and the second modulation scheme may be(4,12,16)32APSK and the γ scheme 32APSK, respectively.

Note that a labelling method with respect to constellation in anin-phase (I)-quadrature-phase (Q) plane of (12,4)16APSK and a labellingmethod with respect to constellation in an in-phase (I)-quadrature-phase(Q) plane of (8,8)16APSK are described in the present embodiment, but alabelling method with respect to constellation in an in-phase(I)-quadrature-phase (Q) plane that is different from the presentembodiment may be applied (there is a possibility of achieving an effectsimilar to the effect of the present embodiment).

Embodiment 2 Example of Pilot Symbols

In the present embodiment, configuration examples of pilot symbols inthe transmission method described in embodiment 1 are described.

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here.

Interference occurs between code (between symbols) of a modulatedsignal, because of non-linearity of the power amplifier of the transmitapparatus. High data reception quality can be achieved by a receiveapparatus by decreasing this intersymbol interference.

In the present example of pilot symbol configuration, a method isdescribed of transmitting baseband signals as pilot symbols, in order todecrease intersymbol interference at a receive apparatus. When datasymbols are configured so that “in a symbol group of at least threeconsecutive symbols (or at least four consecutive symbols), among whicha modulation scheme for each symbol is (12,4)16APSK or (8,8)16APSK,there are no consecutive (12,4)16APSK symbols and there are noconsecutive (8,8)16APSK symbols”, a transmit apparatus generates andtransmits, as pilot symbols, baseband signals corresponding to allconstellation points of (12,4)16APSK on an in-phase (I)-quadrature-phase(Q) plane (in other words, baseband signals corresponding to the 16constellation points of four transmit bits [b₃b₂b₁b₀] from [0000] to[1111]) and baseband signals corresponding to all constellation pointsof (8,8)16APSK on an in-phase (I)-quadrature-phase (Q) plane (in otherwords, baseband signals corresponding to the 16 constellation points offour transmit bits [b₃b₂b₁b₀] from [0000] to [1111]).

Thus, the receive apparatus can estimate intersymbol interference forall constellation points on an in-phase (I)-quadrature-phase (Q) planeof (12,4)16APSK and all constellation points on an in-phase(I)-quadrature-phase (Q) plane of (8,8)16APSK, and therefore there is ahigh possibility of achieving high data reception quality.

In the example illustrated in FIG. 13, the following are transmitted aspilot symbols, in order:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0000] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0001] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b_(b0)]=[0100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0110] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[0111] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1000] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1001] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK; a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1110] of (8,8)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK; and a symbol of a constellation point(baseband signal) corresponding to [b₃b₂b₁b₀]=[1111] of (8,8)16APSK.

The above feature means that:

<1> Symbols corresponding to all constellation points on an in-phase(I)-quadrature-phase (Q) plane of (12,4)16APSK, i.e., the followingsymbols, are transmitted:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK.

Symbols corresponding to all constellation points on an in-phase(I)-quadrature-phase (Q) plane of (8,8)16APSK, i.e., the followingsymbols, are transmitted:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (8, 8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (8, 8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b_(b0)]=[1101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (8,8)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (8,8)16APSK.

<2> In a symbol group composed of consecutive pilot symbols, there areno consecutive (12,4)16APSK symbols and there are no consecutive(8,8)16APSK symbols. According to <1>, a receive apparatus can estimateintersymbol interference with high precision, and can therefore achievehigh data reception quality. Further, according to <2>, an effect isachieved of lowering PAPR.

Note that pilot symbols are not only symbols for estimating intersymbolinterference, and a receive apparatus may use pilot symbols to performestimation of a radio wave propagation environment (channel estimation)between the transmit apparatus and the receive apparatus, and may usepilot symbols to perform frequency offset estimation and timesynchronization.

Operation of a receive apparatus is described with reference to FIG. 2.

In FIG. 2, 210 indicates a configuration of a receive apparatus. Thede-mapper 214 of FIG. 2 performs de-mapping with respect to mapping of amodulation scheme used by the transmit apparatus, for example obtainingand outputting a log-likelihood ratio for each bit. At this time,although not illustrated in FIG. 2, estimation of intersymbolinterference, estimation of a radio wave propagation environment(channel estimation) between the transmit apparatus and the receiveapparatus, time synchronization between the transmit apparatus and thereceive apparatus, and frequency offset estimation between the transmitapparatus and the received apparatus may be performed in order toprecisely perform de-mapping.

Although not illustrated in FIG. 2, the receive apparatus includes anintersymbol interference estimator, a channel estimator, a timesynchronizer, and a frequency offset estimator. These estimators extractfrom receive signals a portion of pilot symbols, for example, andrespectively perform intersymbol interference estimation, estimation ofa radio wave propagation environment (channel estimation) between thetransmit apparatus and the receive apparatus, time synchronizationbetween the transmit apparatus and the receive apparatus, and frequencyoffset estimation between the transmit apparatus and the receiveapparatus. Subsequently, the de-mapper 214 of FIG. 2 inputs theseestimation signals and, by performing de-mapping based on theseestimation signals, performs, for example, calculation of alog-likelihood ratio.

Further, a transmission method of pilot symbols is not limited to theexample illustrated in FIG. 13 as long as the transmission methodsatisfies both <1> and <2> described above. For example, a modulationscheme of the 1st symbol of FIG. 13 may be (8,8)16APSK, and atransmission order of [b₃b₂b₁b₀] may be any transmission order. Further,the number of pilot symbols is not limited to 32 symbols as long as thepilot symbols satisfy both <1> and <2>. Accordingly, when composed of32×N (N being a natural number) symbols, there is an advantage that thenumber of occurrences of each of the following symbols can be equalized:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (8, 8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (8, 8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (8, 8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (8,8)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (8,8)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (8,8)16APSK.

Embodiment 3 Signaling

In the present embodiment, examples are described of various informationsignaled as TMCC information in order to facilitate reception at thereceive apparatus of a transmit signal used in the transmission schemedescribed in embodiment 1 and embodiment 2.

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here.

FIG. 18 illustrates a schematic of a frame of a transmit signal ofadvanced wide band digital satellite broadcasting. (However, FIG. 18 isnot intended to be an exact illustration of a frame of advanced wideband digital satellite broadcasting).

FIG. 18, part (a) indicates a frame along a horizontal axis of time,along which a “#1 symbol group”, a “#2 symbol group”, a “#3 symbolgroup”, . . . are arranged. Each symbol group of the “#1 symbol group”,the “#2 symbol group”, the “#3 symbol group”, . . . is composed of a“synchronization symbol group”, a “pilot symbol group”, a “TMCCinformation symbol group”, and “slots composed of a data symbol group”,as illustrated in FIG. 18, part (a). A “synchronization symbol group”is, for example, a symbol for a receive apparatus to perform timesynchronization and frequency synchronization, and a “pilot symbolgroup” is used by a receive apparatus for processing as described above.

“Slots composed of a data symbol group” is composed of data symbols.Transmission methods used to generate data symbols, including errorcorrection code, coding rate, code length, modulation scheme, etc., areswitchable. Information related to transmission methods used to generatedata symbols, including error correction code, coding rate, code length,modulation scheme, etc., is transmitted to a receive apparatus via a“TMCC information symbol group”.

FIG. 18, part (b), illustrates an example of a “TMCC information symbolgroup”. The following describes in particular a configuration of“transmission mode/slot information” of a “TMCC information symbolgroup”.

FIG. 18, part (c), illustrates a configuration of “transmissionmode/slot information” of a “TMCC information symbol group”. In FIG. 18,part (c), “transmission mode 1” to “transmission mode 8” areillustrated, and “slots composed of data symbol group of #1 symbolgroup”, “slots composed of data symbol group of #2 symbol group”, “slotscomposed of data symbol group of #3 symbol group”, . . . each belong toa respective one of “transmission mode 1” to “transmission mode 8”.

Thus, modulation scheme information for generating symbols of “slotscomposed of a data symbol group” is transmitted by symbols fortransmitting each modulation scheme of a transmission mode in FIG. 18,part (c) (indicated in FIG. 18, part (c), by “modulation scheme oftransmission mode 1”, . . . , “modulation scheme of transmission mode8”).

Further, coding rate information of error correction code for generatingsymbols of “slots composed of a data symbol group” is transmitted bysymbols for transmitting each coding rate of a transmission mode in FIG.18, part (c) (indicated in FIG. 18, part (c), by “coding rate oftransmission mode 1”, . . . , “coding rate of transmission mode 8”).

Table 1 illustrates a configuration of modulation scheme information. InTable 1, for example, when four bits to be transmitted by a symbol fortransmitting a modulation scheme of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0001],a modulation scheme for generating symbols of “slots composed of asymbol group” is π/2 shift binary phase shift keying (BPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0010], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is quadrature phase shift keying (QPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of a “transmission mode/slotinformation” of a “TMCC information symbol group” are [0011], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 8 phase shift keying (8PSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0100], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (12,4)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0101], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (8,8)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0110], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 32 amplitude phase shift keying (32APSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0111], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is a “transmission method mixing (12,4)16APSK symbols and(8,8)16APSK symbols” (this may be the transmission method described inembodiment 1, for example, but the present description also describesother transmission methods (for example, embodiment 4)).

TABLE 1 Modulation scheme information Value Assignment 0000 Reserved0001 π/2 shift BPSK 0010 QPSK 0011 8PSK 0100 (12,4)16APSK 0101(8,8)16APSK 0110 32APSK 0111 Transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols . . . . . . 1111 No scheme assigned

Table 2 illustrates a relationship between coding rates of errorcorrection code and ring ratios when a modulation scheme is(12,4)16APSK. According to R₁ and R₂, used above to representconstellation points in an I-Q plane of (12,4)16APSK, a ring ratioR_((12,4)) of (12,4)16APSK is represented as R_((12,4))=R₂/R₁.

In Table 2, for example, when four bits to be transmitted by a symbolfor transmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen a symbol for transmitting a modulation scheme of a transmissionmode is indicated to be (12,4)16APSK, a ring ratio R_((12,4)) of(12,4)16APSK is 3.09.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 2.97.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 3.93.

TABLE 2 Relationship between coding rates of error correction code andring ratios when modulation scheme is (12,4)16APSK Value Coding rate(approximate value) Ring ratio 0000 41/120 (1/3) 3.09 0001 49/120 (2/5)2.97 0010 61/120 (1/2) 3.93 . . . . . . . . . 1111 No scheme assigned —

Table 3 illustrates a relationship between coding rates of errorcorrection code and ring ratios when a modulation scheme is (8,8)16APSK.As above, according to R₁ and R₂ used in representing the constellationpoints in the I-Q plane of (8,8)16APSK, a ring ratio R_((8,8)) of(8,8)16APSK is represented as R_((8,8))=R₂/R₁. In Table 3, for example,when four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0000], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 41/120 (≈1/3), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (8,8)16APSK, a ring ratio R_((8,8)) of (8,8)16APSK is 2.70.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (8,8)16APSK, a ring ratio R_((8,8)) of (8,8)16APSK is 2.60.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (8,8)16APSK, a ring ratio R_((8,8)) of (8,8)16APSK is 2.50.

TABLE 3 Relationship between coding rates of error correction code andring ratios when a modulation scheme is (8,8)16APSK Value Coding rate(approximate value) Ring ratio 0000 41/120 (1/3) 2.70 0001 49/120 (2/5)2.60 0010 61/120 (1/2) 2.50 . . . . . . . . . 1111 No scheme assigned —

Table 4 illustrates a relationship between coding rates of errorcorrection code and ring ratios when a transmission method mixes(12,4)16APSK symbols and (8,8)16APSK symbols.

In Table 4, for example, when four bits to be transmitted by a symbolfor transmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen symbols for transmitting a modulation scheme of a transmission modeare indicated to be generated by a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols, a ring ratio R_((12,4)) of(12,4)16APSK is 4.20 and a ring ratio R_((8,8)) of (8,8)16APSK is 2.70.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when symbols fortransmitting a modulation scheme of a transmission mode are indicated tobe generated by a transmission method mixing (12,4)16APSK symbols and(8,8)16APSK symbols, a ring ratio R_((12,4)) of (12,4)16APSK is 4.10 anda ring ratio R_((8,8)) of (8,8)16APSK is 2.60.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when symbols fortransmitting a modulation scheme of a transmission mode are indicated tobe generated by a transmission method mixing (12,4)16APSK symbols and(8,8)16APSK symbols, a ring ratio R_((12,4)) of (12,4)16APSK is 4.00 anda ring ratio R_((8,8)) of (8,8)16APSK is 2.50.

TABLE 4 Relationship between coding rates of error correction code andring ratios when transmission method mixes (12,4)16APSK symbols and(8,8)16APSK symbols. Coding rate (12,4)16APSK (8,8)16APSK Value(approximate value) ring ratio ring ratio 0000 41/120 (1/3) 4.20 2.700001 49/120 (2/5) 4.10 2.60 0010 61/120 (1/2) 4.00 2.50 . . . — . . . .. . 1111 No scheme assigned — —

Further, as in FIG. 22, the following transmission is performed by“stream type/relative stream information” of a “TMCC information symbolgroup”.

FIG. 22, part (a) illustrates a configuration of “stream type/relativestream information”. In FIG. 22, part (a), a configuration fortransmitting stream type information is illustrated as an exampleincluding stream 0 to stream 15. In FIG. 22, part (a), “stream type ofrelative stream 0” indicates stream type information of stream 0.

Likewise, “stream type of relative stream 1” indicates stream typeinformation of stream 1.

“Stream type of relative stream 2” indicates stream type information ofstream 2.

“Stream type of relative stream 15” indicates stream type information ofstream 15.

Stream type information for a stream is assumed to be composed of eightbits (however, this is just an example).

FIG. 22, part (b), illustrates examples of assignments to eight bitstream type information.

Eight bit stream type information [00000000] is reserved.

Eight bit stream type information [00000001] indicates that the streamis Moving Picture Experts Group-2 transport stream (MPEG-2TS).

Eight bit stream type information [00000010] indicates that the streamis type-length-value (TLV).

Eight bit stream type information [00000011] indicates that the streamis video (moving image) of resolution approximately 4 k (for example,3840) pixels horizontally by approximately 2 k (for example 2160) pixelsvertically. Video coding information may also be included.

Eight bit stream type information [00000100] indicates that the streamis video (moving image) of resolution approximately 8 k (for example,7680) pixels horizontally by approximately 4 k (for example 4320) pixelsvertically. Video coding information may also be included.

Eight bit stream type information [00000101] indicates that the streamis differential information for generating video (moving image) ofresolution approximately 8 k (for example, 7680) pixels horizontally byapproximately 4 k (for example 4320) pixels vertically from a video(moving image) of resolution approximately 4 k (for example, 3840)pixels horizontally by approximately 2 k (for example 2160) pixelsvertically. Video coding information may also be included. Thisinformation is described further later.

Eight bit stream type information [11111111] is not assigned a type.

The following describes how eight bit stream type information [00000101]is used.

Assume the transmit apparatus transmits a stream of a video #A, which isa video (moving image) of resolution approximately 4 k (for example3840) pixels horizontally by approximately 2 k (for example 2160) pixelsvertically. Thus, the transmit apparatus transmits eight bit stream typeinformation [00000011].

In addition, the transmit apparatus is assumed to transmit differentialinformation for generating video (moving image) of resolutionapproximately 8 k (for example, 7680) pixels horizontally byapproximately 4 k (for example 4320) pixels vertically from a video(moving image) of resolution approximately 4 k (for example, 3840)pixels horizontally by approximately 2 k (for example 2160) pixelsvertically. Thus, the transmit apparatus transmits eight bit stream typeinformation [00000101].

A receive apparatus receives the stream type information [00000011],determines from this information that the stream is a video (movingimage) of resolution approximately 4 k (for example, 3840) pixelshorizontally by approximately 2 k (for example 2160) pixels vertically,and can receive the video #A that is a video (moving image) ofresolution approximately 4 k (for example, 3840) pixels horizontally byapproximately 2 k (for example 2160) pixels vertically.

Further, in addition to the receive apparatus receiving the stream typeinformation [00000011], and determining from this information that thestream is a video (moving image) of resolution approximately 4 k (forexample, 3840) pixels horizontally by approximately 2 k (for example2160) pixels vertically, the receive apparatus receives the stream typeinformation [00000101] and determines from this information that thestream is differential information for generating a video (moving image)of resolution approximately 8 k (for example, 7680) pixels horizontallyby approximately 4 k (for example 4320) pixels vertically from a video(moving image) of resolution approximately 4 k (for example, 3840)pixels horizontally by approximately 2 k (for example 2160) pixelsvertically. Thus, the receive apparatus can obtain a video (movingimage) of resolution approximately 8 k (for example, 7680) pixelshorizontally by approximately 4 k (for example 4320) pixels verticallyof the video #A from both streams.

Note that in order to transmit these streams, the transmit apparatususes, for example, a transmission method described in embodiment 1 andembodiment 2. Further, as described in embodiment 1 and embodiment 2,when the transmit apparatus transmits these streams using modulationscheme of both (12,4)16APSK and (8,8)16APSK, the effects described inembodiment 1 and embodiment 2 can be achieved.

<Receive Apparatus>

The following describes operation of a receive apparatus that receives aradio signal transmitted by the transmit apparatus 700, with referenceto the diagram of a receive apparatus in FIG. 19.

A receive apparatus 1900 of FIG. 19 receives a radio signal transmittedby the transmit apparatus 700 via an antenna 1901. An RF receiver 1902performs processing such as frequency conversion and quadraturedemodulation on a received radio signal, and outputs a baseband signal.

A demodulator 1904 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

A synchronization and channel estimator 1914 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

A control information estimator 1916 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal. Of importance in the present embodiment isthat a receive apparatus demodulates and decodes a symbol transmitting“transmission mode modulation scheme” information and a symboltransmitting “transmission mode coding rate” of “transmission mode/slotinformation” of a “TMCC information symbol group”; and, based on Table1, Table 2, Table 3, and Table 4, the control information estimator 1916generates modulation scheme (or transmission method) information anderror correction code scheme (for example, coding rate of errorcorrection code) information used by “slots composed of a data symbolgroup”, and generates ring ratio information when a modulation scheme(or transmission method) used by “slots composed of a data symbol group”is a transmission method mixing (12,4)16APSK, (8,8)16APSK, 32APSK,(12,4)16APSK symbols and (8,8)16APSK symbols, and outputs theinformation as a portion of a control signal.

A de-mapper 1906 receives a post-filter baseband signal, control signal,and estimated signal as input, determines a modulation scheme (ortransmission method) used by “slots composed of a data symbol group”based on the control signal (in this case, when there is a ring ratio,determination with respect to the ring ratio is also performed),calculates, based on this determination, a log-likelihood ratio (LLR)for each bit included in a data symbol from the post-filter basebandsignal and estimated signal, and outputs the log-likelihood ratios.(However, instead of a soft decision value such as an LLR a harddecision value may be outputted, and a soft decision value instead of anLLR may be outputted.)

A de-interleaver 1908 receives log-likelihood ratios as input,accumulates input, performs de-interleaving (permutes data)corresponding to interleaving used by the transmit apparatus, andoutputs post-de-interleaving log-likelihood ratios.

An error correction decoder 1912 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection coding used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method.

The above describes operation when iterative detection is not performed.The following is supplemental description of operation when iterativedetection is performed. Note that a receive apparatus need not implementiterative detection, and a receive apparatus may be a receive apparatusthat performs initial detection and error detection decoding withoutbeing provided with elements related to iterative detection that aredescribed below.

When iterative detection is performed, the error correction decoder 1912outputs a log-likelihood ratio for each post-decoding bit (note thatwhen only initial detection is performed, output of a log-likelihoodratio for each post decoding bit is not necessary).

An interleaver 1910 interleaves a log-likelihood ratio for eachpost-decoding bit (performs permutation), and outputs apost-interleaving log-likelihood ratio.

The de-mapper 1906 performs iterative detection by usingpost-interleaving log-likelihood ratios, a post-filter baseband signal,and an estimated signal, and outputs a log-likelihood ratio for eachpost-iterative detection bit.

Subsequently, interleaving and error correction code operations areperformed. Thus, these operations are iteratively performed. In thisway, finally the possibility of achieving a preferable decoding resultis increased.

In the above description, a feature thereof is that by a receptionapparatus obtaining a symbol for transmitting a modulation scheme of atransmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group” and a symbol for transmitting coding rate of atransmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group”; a modulation scheme, coding rate of errordetection coding, and, when a modulation scheme is 16APSK, 32APSK, or atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols,ring ratios, are estimated and demodulation and decoding operationsbecome possible.

The above description describes the frame configuration in FIG. 18, butframe configurations applicable to the present invention are not limitedin this way. When a plurality of data symbols exist, a symbol fortransmitting information related to a modulation scheme used ingenerating the plurality of data symbols, and a symbol for transmittinginformation related to an error correction scheme (for example, errorcorrection code, code length of error correction code, coding rate oferror correction code, etc.) exist, any arrangement in a frame may beused with respect to the plurality of data symbols, the symbol fortransmitting information related to a modulation scheme, and the symbolfor transmitting information related to an error correction scheme.Further, symbols other than these symbols, for example symbols forpreamble and synchronization, pilot symbols, reference symbols, etc.,may exist in a frame.

In addition, as a method different to that described above, a symboltransmitting information related to ring ratios may exist, and thetransmit apparatus may transmit the symbol. An example of a symboltransmitting information related to ring ratios is illustrated below.

TABLE 5 Example of symbol transmitting information related to ringratios Value Assignment 00000 (12,4)16APSK ring ratio 4.00 00001(12,4)16APSK ring ratio 4.10 00010 (12,4)16APSK ring ratio 4.20 00011(12,4)16APSK ring ratio 4.30 00100 (8,8)16APSK ring ratio 2.50 00101(8,8)16APSK ring ratio 2.60 00110 (8,8)16APSK ring ratio 2.70 00111(8,8)16APSK ring ratio 2.80 01000 (12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.50 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01001 (12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.60 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01010 (12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.70 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01011 (12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.80 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01100 (12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.50 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01101 (12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.60 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01110 (12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.70 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols 01111 (12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.80 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols . . . . . . 11111 . . .

According to Table 5, when [00000] is transmitted by a symboltransmitting information related to a ring ratio, a data symbol is asymbol of “(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10”.

When [00010] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.20”.

When [00011] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.30”.

When [00100] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(8,8)16APSK ring ratio2.50”.

When [00101] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(8,8)16APSK ring ratio2.60”.

When [00110] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(8,8)16APSK ring ratio2.70”.

When [00111] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(8,8)16APSK ring ratio2.80”.

When [01000] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.00, (8,8)16APSK ring ratio 2.50 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01001] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.00, (8,8)16APSK ring ratio 2.60 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01010] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.00, (8,8)16APSK ring ratio 2.70 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01011] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.00, (8,8)16APSK ring ratio 2.80 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01100] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10, (8,8)16APSK ring ratio 2.50 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01101] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10, (8,8)16APSK ring ratio 2.60 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01110] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10, (8,8)16APSK ring ratio 2.70 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

When [01111] is transmitted by a symbol transmitting information relatedto a ring ratio, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10, (8,8)16APSK ring ratio 2.80 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols”.

Thus, by obtaining a symbol transmitting information related to a ringratio, a receive apparatus can estimate a ring ratio used by a datasymbol, and therefore demodulation and decoding of the data symbolbecomes possible.

Further, ring ratio information may be included in a symbol fortransmitting a modulation scheme. An example is illustrated below.

TABLE 6 Modulation scheme information Value Assignment 00000(12,4)16APSK ring ratio 4.00 00001 (12,4)16APSK ring ratio 4.10 00010(12,4)16APSK ring ratio 4.20 00011 (12,4)16APSK ring ratio 4.30 00100(8,8)16APSK ring ratio 2.50 00101 (8,8)16APSK ring ratio 2.60 00110(8,8)16APSK ring ratio 2.70 00111 (8,8)16APSK ring ratio 2.80 01000(12,4)16APSK ring ratio 4.00, (8,8)16APSK ring ratio 2.50 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01001 (12,4)16APSK ring ratio 4.00, (8,8)16APSK ring ratio 2.60 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01010 (12,4)16APSK ring ratio 4.00, (8,8)16APSK ring ratio 2.70 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01011 (12,4)16APSK ring ratio 4.00, (8,8)16APSK ring ratio 2.80 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01100 (12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.50 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01101 (12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.60 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01110 (12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.70 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols01111 (12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.80 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols. . . . . . 11101 8PSK 11110 QPSK 11111 π/2 shift BPSK

According to Table 6, when [00000] is transmitted by a symboltransmitting modulation scheme information, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10”.

When [00010] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.20”.

When [00011] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.30”.

When [00100] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(8,8)16APSK ring ratio 2.50”.

When [00101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(8,8)16APSK ring ratio 2.60”.

When [00110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(8,8)16APSK ring ratio 2.70”.

When [00111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(8,8)16APSK ring ratio 2.80”.

When [01000] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.50 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01001] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.60 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01010] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.70 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01011] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.00,(8,8)16APSK ring ratio 2.80 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01100] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.50 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.60 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.70 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [01111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio 4.10,(8,8)16APSK ring ratio 2.80 in a transmission method mixing (12,4)16APSKsymbols and (8,8)16APSK symbols”.

When [11101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “8PSK”.

When [11110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “QPSK”.

When [11111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “π/2 shift BPSK”.

Thus, by obtaining a symbol transmitting modulation scheme information,a receive apparatus can estimate a modulation scheme and ring ratio usedby a data symbol, and therefore demodulation and decoding of the datasymbol becomes possible.

Note that in the above description, examples are described including“(12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.80 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSKsymbols”, “(12,4)16APSK”, and “(8,8)16APSK” as selectable modulationschemes (transmission methods), but modulation schemes (transmissionmethods) are not limited to these examples. For example, “(12,4)16APSKring ratio 4.10, (8,8)16APSK ring ratio 2.80 in a transmission methodmixing (12,4)16APSK symbols and (8,8)16APSK symbols” may be included asa selectable modulation scheme (transmission method); “(12,4)16APSK ringratio 4.10, (8,8)16APSK ring ratio 2.80 in a transmission method mixing(12,4)16APSK symbols and (8,8)16APSK symbols” and “(12,4)16APSK” may beincluded as selectable modulation schemes (transmission methods); or“(12,4)16APSK ring ratio 4.10, (8,8)16APSK ring ratio 2.80 in atransmission method mixing (12,4)16APSK symbols and (8,8)16APSK symbols”and “(8,8)16APSK” may be included as selectable modulation schemes(transmission methods).

When a modulation scheme for which a ring ratio can be set is includedamong selectable modulation schemes, the transmit apparatus transmitsinformation related to the ring ratio of the modulation scheme or acontrol symbol that enables estimation of the ring ratio, and thereforea receive apparatus can estimate a modulation scheme and ring ratio of adata symbol, and demodulation and decoding of the data symbol becomespossible.

Embodiment 4

In the present embodiment, an order of generation of a data symbol isdescribed.

FIG. 18, part (a) illustrates a schematic of a frame configuration.

In FIG. 18, part (a), the “#1 symbol group”, the “#2 symbol group”, the“#3 symbol group”, . . . are lined up.

Each symbol group among the “#1 symbol group”, the “#2 symbol group”,the “#3 symbol group”, . . . is herein composed of a “synchronizationsymbol group”, a “pilot symbol group”, a “TMCC information symbolgroup”, and “slots composed of a data symbol group” as illustrated inFIG. 18, part (a).

Here, a configuration scheme is described of data symbol groups in each“slots composed of a data symbol group” among, for example, N symbolgroups including the “#1 symbol group”, the “#2 symbol group”, the “#3symbol group”, . . . , an “#N−1 symbol group”, an “#N symbol group”.

A rule is provided with respect to generation of data symbol groups ineach “slots composed of a data symbol group” among N symbol groups froma “#(β×N+1) symbol group” to a “#(β×N+N) symbol group”. The rule isdescribed with reference to FIG. 20.

In FIG. 20, “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” iswritten, but “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” meansthat the symbol group is generated, as described in embodiment 1, by atransmission method selected from:

-   -   “In a symbol group of at least three consecutive symbols (or at        least four consecutive symbols), among which a modulation scheme        for each symbol is (12,4)16APSK or (8,8)16APSK, there are no        consecutive (12,4)16APSK symbols and there are no consecutive        (8,8)16APSK symbols”; and    -   When each data symbol is either a (12,4)16APSK symbol or an        (8,8)16APSK symbol, three or more consecutive (8,8)16APSK        symbols are not present in a consecutive data symbol group, as        in the examples of FIG. 23.

Thus, “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” satisfies thefeatures of FIG. 20, part (a) to part (f). Note that in FIG. 20, thehorizontal axis is symbols.

FIG. 20, part (a):

When a 32APSK data symbol exists and an (8,8)16APSK data symbol does notexist, a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbolexists after a “32APSK data symbol”, as illustrated in FIG. 20, part(a).

FIG. 20, part (b):

When an (8,8)16APSK data symbol exists, a “(8,8)16APSK symbol and(12,4)16APSK symbol mixed” symbol exists after an “(8,8)16APSK datasymbol”, as illustrated in FIG. 20, part (b).

FIG. 20, part (c):

When a (12,4)16APSK data symbol exists, a “(12,4)16APSK data symbol”exists after a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed”symbol, as illustrated in FIG. 20, part (c).

FIG. 20, part (d):

When an 8PSK data symbol exists and a (12,4)16APSK data symbol does notexist, an “8PSK data symbol” exists after a “(8,8)16APSK symbol and(12,4)16APSK symbol mixed” symbol, as illustrated in FIG. 20, part (d).

FIG. 20, part (e):

When a QPSK data symbol exists, an 8PSK data symbol does not exist, anda (12,4)16APSK data symbol does not exist, a “QPSK data symbol” existsafter a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbol, asillustrated in FIG. 20, part (e).

FIG. 20, part (f):

When a π/2 shift BPSK data symbol exists, a QPSK data symbol does notexist, an 8PSK data symbol does not exist, and a (12,4)16APSK datasymbol does not exist, a “π/2 shift BPSK data symbol” exists after a“(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbol, asillustrated in FIG. 20, part (f).

When symbols are arranged as described above, there is an advantage thata receive apparatus can easily perform automatic gain control (AGC)because a signal sequence is arranged in order of modulation schemes(transmission methods) of high peak power.

FIG. 21 illustrates a method of configuring a “(8,8)16APSK symbol and(12,4)16APSK symbol mixed” symbol, as described above.

Assume that a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbolof a coding rate X of error correction code and a “(8,8)16APSK symboland (12,4)16APSK symbol mixed” symbol of a coding rate Y of errorcorrection code exist. Also assume that a relationship X>Y is satisfied.

When the above is true, a “(8,8)16APSK symbol and (12,4)16APSK symbolmixed” symbol of a coding rate Y of error correction code is arrangedafter a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbol of acoding rate X of error correction code.

As in FIG. 21, assume that a “(8,8)16APSK symbol and (12,4)16APSK symbolmixed” symbol of a coding rate 1/2 of error correction code, a“(8,8)16APSK symbol and (12,4)16APSK symbol mixed” symbol of a codingrate 2/3 of error correction code, and a “(8,8)16APSK symbol and(12,4)16APSK symbol mixed” symbol of a coding rate 3/4 of errorcorrection code exist. Thus, from the above description, as illustratedin FIG. 21, symbols are arranged in the order of a “(8,8)16APSK symboland (12,4)16APSK symbol mixed” symbol of a coding rate 3/4 of errorcorrection code, a “(8,8)16APSK symbol and (12,4)16APSK symbol mixed”symbol of a coding rate 2/3 of error correction code, and a “(8,8)16APSKsymbol and (12,4)16APSK symbol mixed” symbol of a coding rate 1/2 oferror correction code.

Embodiment 5

According to embodiment 1 to embodiment 4, methods of switching(12,4)16APSK symbols and (8,8)16APSK symbols in a transmit frame,methods of configuring pilot symbols, methods of configuring controlinformation including TMCC, etc., have been described.

Methods achieving a similar effect to embodiment 1 to embodiment 4 arenot limited to methods using (12,4)16APSK symbols and (8,8)16APSKsymbols in a transmit frame, and a method using (12,4)16APSK symbols andnon-uniform (NU)-16QAM symbols can also achieve a similar effect toembodiment 1 to embodiment 4. In other words, NU-16QAM symbols may beused instead of (8,8)16APSK symbols in embodiment 1 to embodiment 4 (themodulation scheme used in combination is (12,4)16APSK). Accordingly, thepresent embodiment primarily describes using NU-16QAM symbols instead of(8,8)16APSK symbols.

<Constellation>

The following describes constellation and assignment of bits to eachconstellation point (labelling) of NU-16QAM performed by the mapper 708of FIG. 7.

FIG. 26 illustrates an example of labelling a constellation of NU-16QAMin an in-phase (I)-quadrature-phase (Q) plane. In embodiment 1 toembodiment 4, description is provided using ring ratios, but here an“amplitude ratio” is defined instead of a ring ratio. When R₁ and R₂ aredefined as in FIG. 26 (here, R₁ is a real number greater than zero andR₂ is a real number greater than zero, and R₁<R₂), an amplitude ratioA_(r)=R₂/R₁. Thus, an amplitude ratio of NU-16QAM is applicable insteadof a ring ratio of (8,8)16APSK in embodiment 1 to embodiment 4.

Coordinates of each constellation point of NU-16QAM on the I-Q plane areas follows.

Constellation point 1-1 [0000] . . . (R₂,R₂)

Constellation point 1-2 [0001] . . . (R₂,R₁)

Constellation point 1-3 [0101] . . . (R₂,−R₁)

Constellation point 1-4 [0100] . . . (R₂,−R₂)

Constellation point 2-1 [0010] . . . (R₁,R₂)

Constellation point 2-2 [0011] . . . (R₁,R₁)

Constellation point 2-3 [0111] . . . (R₁,−R₁)

Constellation point 2-4 [0110] . . . (R₁,−R₂)

Constellation point 3-1 [1010] . . . (−R₁,R₂)

Constellation point 3-2 [1011] . . . (−R₁,R₁)

Constellation point 3-3 [1111] . . . (−R₁,−R₁)

Constellation point 3-4 [1110] . . . (−R₁,−R₂)

Constellation point 4-1 [1000] . . . (−R₂,R₂)

Constellation point 4-2 [1001] . . . (−R₂,R₁)

Constellation point 4-3 [1101] . . . (−R₂,−R₁)

Constellation point 4-4 [1100] . . . (−R₂,−R₂)

Further, for example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (R₂,R₂)

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₂,R₂). Asanother example, the following relationship is disclosed above:

Constellation point 4-4 [1100] . . . (−R₂,−R₂)

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1100], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(−R₂,−R₂).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

<Transmission Output>

In order to achieve the same transmission output for (12,4)16APSKsymbols and NU-16QAM symbols, the following normalization coefficientmay be used. The normalization coefficient for (12,4)16APSK symbols isas described in embodiment 1. A normalization coefficient for NU-16QAMsymbols is defined by the following formula.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Math}\mspace{14mu} 25} \right\rbrack} & \; \\{a_{{NU} - {16\; {QAM}}} = \frac{z}{\sqrt{\left( {{4 \times 2 \times R_{1}^{2}} + {4 \times 2 \times R_{2}^{2}} + {8 \times \left( {R_{1}^{2} + R_{2}^{2}} \right)}} \right)/16}}} & \left( {{Math}\mspace{14mu} 25} \right)\end{matrix}$

Prior to normalization, the in-phase component of a baseband signal isI_(b) and the quadrature component of the baseband signal is Q_(b).After normalization, the in-phase component of the baseband signal isI_(n) and the quadrature component of the Baseband signal is Q_(n).Thus, when a modulation scheme is NU-16QAM, (I_(n),Q_(n))=(a_(NU-16QAM)×I_(b), a_(NU-16QAM)×Q_(b)) holds true.

When a modulation scheme is NU-16QAM, the in-phase component I_(b) andquadrature component Q_(b) are the in-phase component I and quadraturecomponent Q, respectively, of a baseband signal after mapping that isobtained by mapping based on FIG. 26. Accordingly, when a modulationscheme is NU-16QAM, the following relationships hold true.

Constellation point 1-1 [0000] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₂)

Constellation point 1-2 [0001] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₁)

Constellation point 1-3 [0101] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₁)

Constellation point 1-4 [0100] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₂)

Constellation point 2-1 [0010] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₁,a_(NU-16QAM)×R₂)

Constellation point 2-2 [0011] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₁,a_(NU-16QAM)×R₁)

Constellation point 2-3 [0111] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₁,−a_(NU-16QAM)×R₁)

Constellation point 2-4 [0110] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₁,−a_(NU-16QAM)×R₂)

Constellation point 3-1 [1010] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₁,a_(NU-16QAM)×R₂)

Constellation point 3-2 [1011] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₁,a_(NU-16QAM)×R₁)

Constellation point 3-3 [1111] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₁,−a_(NU-16QAM)×R₁)

Constellation point 3-4 [1110] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₁,−a_(NU-16QAM)×R₂)

Constellation point 4-1 [1000] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₂)

Constellation point 4-2 [1001] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₁)

Constellation point 4-3 [1101] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₁)

Constellation point 4-4 [1100] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₂)

Further, for example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₂)

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], (I_(n), Q_(n))=(a_(NU-16QAM)×R₂,a_(NU-16QAM)×R₂). As another example, the following relationship isdisclosed above:

Constellation point 4-4 [1100] . . . (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₂)

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1100], (I_(n), Q_(n))=(−a_(NU-16QAM)×R₂,−a_(NU-16QAM)×R₂).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

Thus, the mapper 708 outputs I_(n) and Q_(n) as described above as anin-phase component and a quadrature component, respectively, of abaseband signal.

According to R₁ and R₂ used in representing the constellation points inthe I-Q plane of (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSKrepresents R_((12,4))=R₂/R₁.

When R₁ and R₂ are defined as in FIG. 26, an amplitude ratio of NU-16QAMis defined as A_(r)=R₂/R₁.

Thus, an effect is obtained that “when A_(r)<R_((12,4)), the probabilityof further lowering PAPR is high”.

This is because a modulation scheme likely to control peak power isNU-16QAM. Peak power generated by NU-16QAM is likely to increase asA_(r) increases. Accordingly, in order to avoid increasing peak power,setting A_(r) low is preferable. On the other hand, there is a highdegree of freedom for R_((12,4)) of (12,4)16APSK as long as a value isset for which BER properties are good. Thus, it is likely that whenA_(r)<R_((12,4)) a lower PAPR can be obtained.

However, even when A_(r)>R_((12,4)), an effect of lowering PAPR ofNU-16QAM can be obtained. Accordingly, when focusing on improving BERproperties, A_(r)>R_((12,4)) may be preferable.

<Labelling and Constellations of NU-16QAM>

[NU-16QAM Labelling]

Here, labelling of NU-16QAM is described. Labelling is the relationshipbetween four bits [b₃b₂b₁b₀], which are input, and arrangement ofconstellation points in an in-phase (I)-quadrature-phase (Q) plane. FIG.26 illustrates an example of NU-16QAM labelling, but as long aslabelling satisfies <Condition 5> and <Condition 6>, below, labellingneed not conform to FIG. 26.

For the purposes of description, the following definitions are used.

When four bits to be transmitted are [b_(a3)b_(a2)b_(a1)≠b_(a0)], aconstellation point A is provided in the in-phase (I)-quadrature-phase(Q) plane, and when four bits to be transmitted are[b_(b3)b_(b2)b_(b1)b_(b0)], a constellation point B is provided in thein-phase (I)-quadrature-phase (Q) plane.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as zero.

Further, the following definitions are made.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as four.

Thus, group definitions are performed.

With respect to constellation point 1-1, constellation point 1-2,constellation point 1-3, constellation point 1-4, constellation point2-1, constellation point 2-2, constellation point 2-3, constellationpoint 2-4, constellation point 3-1, constellation point 3-2,constellation point 3-3, constellation point 3-4, constellation point4-1, constellation point 4-2, constellation point 4-3, and constellationpoint 4-4 in the above description of NU-16QAM, constellation point 1-1,constellation point 1-2, constellation point 1-3, and constellationpoint 1-4 are defined as group 1. In the same way, constellation point2-1, constellation point 2-2, constellation point 2-3, and constellationpoint 2-4 are defined as group 2; constellation point 3-1, constellationpoint 3-2, constellation point 3-3, and constellation point 3-4 aredefined as group 3; and constellation point 4-1, constellation point4-2, constellation point 4-3, and constellation point 4-4 are defined asgroup 4.

The following two conditions are provided.

<Condition 5>

X represents 1, 2, 3, and 4. All values of X satisfy the following:

The number of different bits of labelling between constellation pointX-1 and constellation point X-2 is one.

The number of different bits of labelling between constellation pointX-2 and constellation point X-3 is one.

The number of different bits of labelling between constellation pointX-3 and constellation point X-4 is one.

<Condition 6>

A value u represents 1, 2, and 3, and a value v represents 1, 2, 3, and4. All values of u and all values of v satisfy the following:

The number of different bits of labelling between constellation pointu−v and constellation point (u+1)−v is one.

By satisfying the above conditions, the number of different bits oflabelling among constellation points that are near each other in anin-phase (I)-quadrature-phase (Q) plane is low, and therefore thepossibility of a receive apparatus achieving high data reception qualityis increased. Thus, when a receive apparatus performs iterativedetection, the possibility of the receive apparatus achieving high datareception quality is increased.

When forming a symbol by NU-16QAM, as above, and (12,4)16APSK, and whenimplemented similarly to embodiment 1, any of the following transmissionmethods may be considered.

-   -   In a symbol group of at least three consecutive symbols (or at        least four consecutive symbols), among which a modulation scheme        for each symbol is (12,4)16APSK or NU-16QAM, there are no        consecutive (12,4)16APSK symbols and there are no consecutive        NU-16QAM symbols.    -   In a “symbol group of period (cycle) M”, the number of NU-16QAM        symbols is one greater than the number of (12,4)16APSK symbols,        in other words the number of (12,4)16APSK symbols is N and the        number of NU-16QAM symbols is N+1. Note that N is a natural        number. Thus, in a “symbol group of period (cycle) M”, there are        no consecutive NU-16QAM symbols or there is only 1 position at        which two consecutive NU-16QAM symbols exist. Accordingly, there        are no cases of three or more consecutive NU-16QAM symbols.    -   When each data symbol is either a (12,4)16APSK symbol or an        NU-16QAM symbol, three or more consecutive NU-16QAM symbols are        not present in a consecutive data symbol group.

Thus, by replacing description related to (8,8)16APSK symbols withNU-16QAM for portions of embodiment 1 to embodiment 4 in which(12,4)16APSK symbols and (8,8)16APSK symbols are described (for example,transmission method, pilot symbol configuration method, receiveapparatus configuration, control information configuration includingTMCC, etc.), a transmission method using (12,4)16APSK symbols andNU-16QAM can be implemented in the same way as described in embodiment 1to embodiment 4.

Embodiment 6

In the present embodiment, an example is described of application towide band digital satellite broadcasting of the transmission method, thetransmit apparatus, the reception method, and the receive apparatusdescribed in embodiment 1 to embodiment 5.

FIG. 27 illustrates a schematic of wide band digital satellitebroadcasting. A satellite 2702 in FIG. 27 transmits a transmit signal byusing the transmission method described in embodiment 1 to embodiment 5.This transmit signal is received by a terrestrial receive apparatus.

On the other hand, data for transmission by the satellite 2702 via amodulated signal is transmitted by a ground station 2701 in FIG. 27.Accordingly, the ground station 2701 transmits a modulation signalincluding data for transmission by a satellite. Thus, the satellite 2702receives a modulated signal transmitted by the ground station 2701, andtransmits data included in the modulated signal by using a transmissionmethod described in embodiment 1 to embodiment 5.

Embodiment 7

In the present embodiment, description is provided of variousinformation configuration examples signaled as TMCC information forsmooth reception at a receive apparatus side performed by a transmitapparatus using a transmission method described in embodiment 1,embodiment 2, embodiment 5, etc.

In order to reduce distortion generated by a power amplifier included inthe radio section 712 of the transmit apparatus in FIG. 7, there is amethod of compensating for the distortion of the power amplifier oracquiring backoff information (difference value between operating pointoutput of a modulated signal and saturation point output of anon-modulated signal).

In wide band digital satellite broadcasting, in relation to distortionof a power amplifier, “satellite output backoff” information istransmitted in TMCC information by a transmit apparatus.

In the present embodiment, a method of transmitting accurate informationrelated to distortion of a power amplifier and a configuration of TMCCinformation are described. By transmission of the information describedbelow, a receive apparatus can receive a modulated signal having littledistortion, and therefore an effect can be achieved of improving datareception quality.

Transmission of “whether power amplifier performed distortioncompensation” information and “index indicating degree of effect ofdistortion compensation of power amplifier” information as TMCCinformation is disclosed herein.

TABLE 7 Information related to distortion compensation of poweramplifier Value Assignment 0 Distortion compensation of power amplifierOFF 1 Distortion compensation of power amplifier ON

Table 7 indicates a specific example of configuration of informationrelated to distortion compensation of a power amplifier. As illustratedin FIG. 7, a transmit apparatus transmits “0”, when distortioncompensation of a power amplifier is OFF, or “1”, when distortioncompensation of a power amplifier is ON, as, for example, a portion ofTMCC information (a portion of control information).

TABLE 8 Information related to index indicating degree of effect ofdistortion compensation of power amplifier Value Assignment 00 Betweencode (intersymbol) interference: High 01 Between code (intersymbol)interference: Medium 10 Between code (intersymbol) interference: Low 11—

Table indicates a specific example of configuration of informationrelated to an index indicating degrees of effect of distortioncompensation of a power amplifier. When between code (intersymbol)interference is high, the transmit apparatus transmits “00”. Whenbetween code (intersymbol) interference is of a medium degree, thetransmit apparatus transmits “01”. When between code (intersymbol)interference is low, the transmit apparatus transmits “10”.

In Table 2, Table 3, and Table 4 of embodiment 3, configurations areillustrated according to which a ring ratio is determined when a codingrate of error correction code is determined.

In the present embodiment, a different method is disclosed wherein aring ratio is determined based on information related to distortioncompensation of a power amplifier and/or information related to an indexindicating a degree of effect of distortion compensation of a poweramplifier and/or “satellite output backoff” information; and even when acoding rate of error correction code is set as A (even when a value isset), a transmit apparatus selects a ring ratio from among a pluralityof candidates. As TMCC information, the transmit apparatus can notify areceive apparatus of modulation scheme information and ring ratioinformation by using the “modulation scheme information” of Table 1and/or the “information related to ring ratio” of Table 5 and/or the“modulation scheme information” of Table 6.

FIG. 28 illustrates a block diagram related to ring ratio determinationin connection with the above description. A ring ratio determiner 2801of FIG. 28 receives “modulation scheme information”, “coding rate oferror correction code information”, “satellite output backoffinformation”, “information related to distortion compensation of poweramplifier (ON/OFF information)”, and an “index indicating degree ofeffect of distortion compensation of power amplifier” as input, uses allof this information or a portion of this information, determines a ringratio when a modulation scheme (or transmission method) requires a ringratio setting (for example, a transmission method using (8,8)16APSK,(12,4)16APSK, or a combination of (8,8)16APSK and (12,4)16APSK), andoutputs ring ratio information that is determined. Subsequently, basedon this ring ratio information, a mapper of the transmit apparatusperforms mapping, and this ring ratio information is, for example,transmitted by the transmit apparatus to a receive apparatus as controlinformation as in Table 5 and Table 6.

Note that a characteristic point of this embodiment is that when amodulation scheme A and coding rate B are selected, ring ratio can beset from a plurality of candidates.

For example, when a modulation scheme is (12,4)16APSK and a coding rateof error correction code is 61/129 (approximately 1/2), three types ofring ratio, C, D, and E, are candidates as a ring ratio. Thus, whichvalue of ring ratio to use can be determined according to backoff statusand information related to distortion compensation of a power amplifier(ON/OFF information). For example, when distortion compensation of apower amplifier is ON, a ring ratio may be selected that improves datareception quality of a receive apparatus, and when distortioncompensation of a power amplifier is OFF and backoff is low, a ringratio may be selected that decreases PAPR (ring ratio may be selected insimilar ways for other coding rates, etc.). Note that this selectionmethod can be applied in the same way when a modulation scheme is(8,8)16APSK, and when a transmission method is a transmission methodcombining (8,8)16APSK and (12,4)16APSK as described in embodiment 1.

According to the operations above, an effect is achieved of improvingdata reception quality of a receive apparatus and reducing load of atransmit power amplifier.

Embodiment 8

In embodiment 7 a case is described in which NU-16QAM symbols are usedinstead of (8,8)16APSK symbols in embodiment 1 to embodiment 4. In thepresent embodiment, (4,8,4)16APSK is disclosed as an extension ofNU-16QAM (NU-16QAM is one example of (4.8.4)16APSK).

In the present embodiment, a case is described in which (4,8,4)16APSKsymbols are used instead of (8,8)16APSK symbols in embodiment 1 toembodiment 4.

According to embodiment 1 to embodiment 4, methods of switching(12,4)16APSK symbols and (8,8)16APSK symbols in a transmit frame,methods of configuring pilot symbols, methods of configuring controlinformation including TMCC, etc., have been described.

Methods achieving a similar effect to embodiment 1 to embodiment 4 arenot limited to methods using (12,4)16APSK symbols and (8,8)16APSKsymbols in a transmit frame, and a method using (12,4)16APSK symbols and(4,8,4)16APSK symbols can also achieve a similar effect to embodiment 1to embodiment 4. In other words, (4,8,4)16APSK symbols may be usedinstead of (8,8)16APSK symbols in embodiment 1 to embodiment 4 (themodulation scheme used in combination is (12,4)16APSK).

Accordingly, the present embodiment primarily describes using(4,8,4)16APSK symbols instead of (8,8)16APSK symbols.

<Constellation>

As illustrated in FIG. 30, constellation points of (4,8,4)16APSK mappingare arranged on three concentric circles having different radii(amplitude components) in an in-phase (I)-quadrature-phase (Q) plane. Inthe present description, among these concentric circles, a circle havingthe largest radius R₃ is called an “outer circle”, a circle having anintermediate radius R₂ is called a “mid circle”, and a circle having thesmallest radius R₁ is called an “inner circle”. When R₁, R₂, and R₃ aredefined as in FIG. 30 (R₁ being a real number greater than zero, R₂being a real number greater than zero, and R₃ being a real numbergreater than zero, R₁<R₂<R₃).

Further, four constellation points are arranged on the circumference ofthe outer circle, eight constellation points are arranged on thecircumference of the mid circle, and four constellation points arearranged on the circumference of the inner circle. The (4,8,4) in(4,8,4)16APSK refers to the four, eight, four constellation points inthe order of the outer circle, the mid circle, and the inner circle.

The following describes a constellation and assignment (labelling) ofbits to each constellation point of (4,8,4)16APSK performed by themapper 708 of FIG. 7.

FIG. 30 illustrates an example of labelling a constellation of(4,8,4)16APSK in an in-phase (I)-quadrature-phase (Q) plane. Inembodiment 1 to embodiment 4, ring ratio is described, but in the caseof (4,8,4)16APSK, two ring ratios are defined. A first ring ratio isr₁=R₂/R₁, and another ring ratio is r₂=R₃/R₁. Thus, two ring ratios of(4,8,4)16APSK, r₁=R₂/R₁ and r₂=R₃/R₁, are applicable instead of the ringratio of (8,8)16APSK in embodiment 1 to embodiment 4.

Coordinates of each constellation point of (4,8,4)16APSK on the I-Qplane are as follows.

Constellation point 1-1 [0000] . . . (R₃ cos(π/4),R₃ sin(π/4))

Constellation point 1-2 [0001] . . . (R₂ cos λ,R₂×sin λ)

Constellation point 1-3 [0101] . . . (R₂ cos(−λ),R₂×sin(−λ))

Constellation point 1-4 [0100] . . . (R₃ cos(−π/4),R₃ sin(−π/4))

Constellation point 2-1 [0010] . . . (R₂ cos(−λ+π/2),R₂×sin(−λ+π/2))

Constellation point 2-2 [0011] . . . (R₁ cos(π/4),R₁ sin(π/4))

Constellation point 2-3 [0111] . . . (R₁ cos(−π/4),R₁ sin(−π/4))

Constellation point 2-4 [0110] . . . (R₂ cos(λ−π/2),R₂×sin(λ−π/2))

Constellation point 3-1 [1010] . . . (R₂ cos(λ+π/2),R₂×sin(λ+π/2))

Constellation point 3-2 [1011] . . . (R₁ cos(3π/4),R₁ sin(3π/4))

Constellation point 3-3 [1111] . . . (R₁ cos(−3π/4),R₁ sin(−3π/4))

Constellation point 3-4 [1110] . . . (R₂ cos(−λ−π/2),R₂×sin(−λ−π/2))

Constellation point 4-1 [1000] . . . (R₃ cos(3π/4),R₃ sin(3π/4))

Constellation point 4-2 [1001] . . . (R₂ cos(π−λ),R₂×sin(π−λ))

Constellation point 4-3 [1101] . . . (R₂ cos(−π+λ),R₂×sin(−π+λ))

Constellation point 4-4 [1100] . . . (R₃ cos(−3π/4),R₃ sin(−3π/4))

With respect to phase, the unit used is radians. Accordingly, forexample, referring to R₃ cos(π/4), the unit of π/4 is radians.Hereinafter, the unit of phase is radians. Further, λ is greater thanzero radians and smaller than π/4 (0 radians <λ<π/4 radians).

Further, for example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (R₃ cos(π/4),R₃ sin(π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₃cos(π/4),R₃ sin(π/4)).

As another example, the following relationship is disclosed above:

Constellation point 4-4 [1100] . . . (R₃ cos(−3π/4),R₃ sin(−3π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1100], an in-phase component I and quadrature componentQ of a baseband signal after mapping are defined as (I,Q)=(R₃cos(−3π/4),R₃ sin(−3π/4)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

<Transmission Output>

In order to achieve the same transmission output for (12,4)16APSKsymbols and (4,8,4)16APSK symbols, the following normalizationcoefficient may be used. The normalization coefficient for (12,4)16APSKsymbols is as described in embodiment 1. The normalization coefficientfor (4,8,4)16APSK symbols is defined by the following formula.

$\begin{matrix}\left\lbrack {{Math}\mspace{14mu} 26} \right\rbrack & \; \\{{a\left( {4,8,4} \right)} = \frac{z}{\sqrt{\left( {{4 \times R_{1}^{2}} + {8 \times R_{2}^{2}} + {4 \times R_{3}^{2}}} \right)/16}}} & \left( {{Math}\mspace{14mu} 26} \right)\end{matrix}$

Prior to normalization, the in-phase component of a baseband signal isI_(b) and the quadrature component of the baseband signal is Q_(b).After normalization, the in-phase component of the baseband signal isI_(n) and the quadrature component of the baseband signal is Q_(n).Thus, when a modulation scheme is (4,8,4)16APSK, (I_(n),Q_(n))=(a_((4,8,4))×I_(b), a_((4,8,4))×Q_(b)) holds true.

When a modulation scheme is (4,8,4)16APSK, the in-phase component I_(b)and quadrature component Q_(b) are the in-phase component I andquadrature component Q, respectively, of a baseband signal after mappingthat is obtained by mapping based on FIG. 30. Accordingly, when amodulation scheme is (4,8,4)16APSK, the following relationships holdtrue.

Constellation point 1-1 [0000] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(π/4), a_((4,8,4))×R₃ sin(π/4))

Constellation point 1-2 [0001] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂ cosλ, a_((4,8,4))×R₂×sin λ)

Constellation point 1-3 [0101] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(−λ), a_((4,8,4)) R₂×sin(−λ))

Constellation point 1-4 [0100] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(−π/4), a_((4,8,4))×R₃ sin(−π/4))

Constellation point 2-1 [0010] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(−λ+π/2), a_((4,8,4))×R₂×sin(−λ+π/2))

Constellation point 2-2 [0011] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₁cos(π/4), a_((4,8,4))×R₁ sin(π/4))

Constellation point 2-3 [0111] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₁cos(−π/4), a_((4,8,4))×R₁ sin(−π/4))

Constellation point 2-4 [0110] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(λ−π/2), a_((4,8,4))×R₂ sin(λ−π/2))

Constellation point 3-1 [1010] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(λ+π/2), a_((4,8,4))×R₂×sin(λ+7π/2))

Constellation point 3-2 [1011] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₁cos(3π/4), a_((4,8,4))×R₁ sin(3π/4))

Constellation point 3-3 [1111] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₁cos(−3π/4), a_((4,8,4))×R₁ sin(−3π/4))

Constellation point 3-4 [1110] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(−λ−π/2), a_((4,8,4))×R₂×sin(−λ−π/2))

Constellation point 4-1 [1000] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(3π/4), a_((4,8,4))×R₃ sin(3π/4))

Constellation point 4-2 [1001] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(π−λ), a_((4,8,4))×R₂ sin(π−λ))

Constellation point 4-3 [1101] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₂cos(−π+λ), a_((4,8,4))×R₂×sin(−π+λ))

Constellation point 4-4 [1100] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(−3π/4), a_((4,8,4))×R₃ sin(−3π/4))

Further, for example, the following relationship is disclosed above:

Constellation point 1-1 [0000] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(π/4), a_((4,8,4))×R₃ sin(π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[0000], (I_(n), Q_(n))=(a_((4,8,4))×R₃ cos(λ/4),a_((4,8,4))×R₃ sin(π/4)). As another example, the following relationshipis disclosed above:

Constellation point 4-4 [1100] . . . (I_(n), Q_(n))=(a_((4,8,4))×R₃cos(−3π/4), a_((4,8,4))R₃ sin(−3π/4))

In data that is inputted to the mapper 708, this means that when fourbits [b₃b₂b₁b₀]=[1100], (I_(n), Q_(n))=(a_((4,8,4))×R₃ cos(−3π/4),a_((4,8,4))×R₃ sin(−3π/4)).

This holds true for all of constellation point 1-1, constellation point1-2, constellation point 1-3, constellation point 1-4, constellationpoint 2-1, constellation point 2-2, constellation point 2-3,constellation point 2-4, constellation point 3-1, constellation point3-2, constellation point 3-3, constellation point 3-4, constellationpoint 4-1, constellation point 4-2, constellation point 4-3, andconstellation point 4-4.

Thus, the mapper 708 outputs I_(n) and Q_(n) as described above as anin-phase component and a quadrature component, respectively, of abaseband signal.

<Labelling and Constellations of (4,8,4)16APSK>

[Labelling of (4,8,4)16APSK]

The following describes labelling of (4,8,4)16APSK. Labelling is therelationship between four bits [b₃b₂b₁b₀], which are input, andarrangement of constellation points in an in-phase (I)-quadrature-phase(Q) plane. An example of labelling of (4,8,4)16APSK is illustrated inFIG. 30, but labelling need not conform to FIG. 30 as long as labellingsatisfies the following <Condition 7> and <Condition 8>.

For the purposes of description, the following definitions are used.

When four bits to be transmitted are [b_(a3)b_(a2)b_(a1)b_(a0)], aconstellation point A is provided in the in-phase (I)-quadrature-phase(Q) plane, and when four bits to be transmitted are[b_(b3)b_(b2)b_(b1)b_(b0)], a constellation point B is provided in thein-phase (I)-quadrature-phase (Q) plane.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as zero.

Further, the following definitions are made.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as one.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as two.

When b_(a3)=b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)=b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)=b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)=b_(b0), thenumber of different bits of labelling is defined as three.

When b_(a3)≠b_(b3), b_(a2)≠b_(b2), b_(a1)≠b_(b1), and b_(a0)≠b_(b0), thenumber of different bits of labelling is defined as four.

Thus, group definitions are performed. With respect to constellationpoint 1-1, constellation point 1-2, constellation point 1-3,constellation point 1-4, constellation point 2-1, constellation point2-2, constellation point 2-3, constellation point 2-4, constellationpoint 3-1, constellation point 3-2, constellation point 3-3,constellation point 3-4, constellation point 4-1, constellation point4-2, constellation point 4-3, and constellation point 4-4 in the abovedescription of (4,8,4)16APSK, constellation point 1-1, constellationpoint 1-2, constellation point 1-3, and constellation point 1-4 aredefined as group 1.

In the same way, constellation point 2-1, constellation point 2-2,constellation point 2-3, and constellation point 2-4 are defined asgroup 2; constellation point 3-1, constellation point 3-2, constellationpoint 3-3, and constellation point 3-4 are defined as group 3; andconstellation point 4-1, constellation point 4-2, constellation point4-3, and constellation point 4-4 are defined as group 4.

The following two conditions are provided.

<Condition 7>

X represents 1, 2, 3, and 4. All values of X satisfy the following:

The number of different bits of labelling between constellation pointX-1 and constellation point X-2 is one.

The number of different bits of labelling between constellation pointX-2 and constellation point X-3 is one.

The number of different bits of labelling between constellation pointX-3 and constellation point X-4 is one.

<Condition 8>

A value u represents 1, 2, and 3, and a value v represents 1, 2, 3, and4. All values of u and all values of v satisfy the following:

The number of different bits of labelling between constellation pointu−v and constellation point (u+1)−v is one.

By satisfying the above conditions, the number of different bits oflabelling among constellation points that are near each other in anin-phase (I)-quadrature-phase (Q) plane is low, and therefore thepossibility of a receive apparatus achieving high data reception qualityis increased. Thus, when a receive apparatus performs iterativedetection, the possibility of the receive apparatus achieving high datareception quality is increased.

[Constellation of (4,8,4)16APSK]

The above describes constellation and labelling in an in-phase(I)-quadrature-phase (Q) plane of FIG. 30, but constellation andlabelling in an in-phase (I)-quadrature-phase (Q) plane is not limitedto this example. For example, labelling of coordinates on an I-Q planeof each constellation point of (4,8,4)16APSK may be performed asfollows.

Coordinates on an I-Q plane of the constellation point 1-1 [0000]: (cosθ×R₃×cos(π/4)−sin θ×R₃×sin(π/4), sin θ×R₃×cos(π/4)+cos θ×R₃×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-2 [0001]: (cosθ×R₂×cos λ−sin θ×R₂×sin λ, sin θ×R₂×cos λ+cos θ×R₂×sin λ)

Coordinates on an I-Q plane of the constellation point 1-3 [0101]: (cosθ×R₂×cos(−λ)−sin θ×R₂×sin(−λ), sin θ×R₂×cos(−λ)+cos θ×R₂×sin(−λ))

Coordinates on an I-Q plane of the constellation point 1-4 [0100]: (cosθ×R₃×cos(−π/4)−sin θ×R₃×sin(−π/4), sin θ×R₃×cos(−π/4)+cosθ×R₃×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 2-1 [0010]: (cosθ×R₂×cos(−λ+π/2)−sin θ×R₂×sin(−λ+π/2), sin θ×R₂×cos(−λ+π/2)+cosθ×R₂×sin(−λ+π/2))

Coordinates on an I-Q plane of the constellation point 2-2 [0011]: (cosθ×R₁×cos(π/4)−sin θ×R₁×sin(π/4), sin θ×R₁×cos(π/4)+cos θ×R₁×sin(π/4))

Coordinates on an I-Q plane of the constellation point 2-3 [0111]: (cosθ×R₁×cos(−π/4)−sin θ×R₁×sin(−π/4), sin θ×R₁×cos(−π/4)+cosθ×R₁×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 2-4 [0110]: (cosθ×R₂ cos(−π/2)−sin θ×R₂×sin(−π/2), sin θ×R₂×cos(λ−π/2)+cosθ×R₂×sin(−π/2))

Coordinates on an I-Q plane of the constellation point 3-1 [1010]: (cosθ×R₂ cos(λ+π/2)−sin θ×R₂×sin(+π/2), sin θ×R₂ cos(λ+π/2)+cosθ×R₂×sin(+π/2))

Coordinates on an I-Q plane of the constellation point 3-2 [1011]: (cosθ×R₁×cos(3π/4)−sin θ×R₁×sin(3π/4), sin θ×R₁×cos(3π/4)+cosθ×R₁×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 3-3 [1111]: (cosθ×R₁×cos(−3π/4)−sin θ×R₁×sin(−3π/4), sin θ×R₁×cos(−3π/4)+cosθ×R₁×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-4 [1110]: (cosθ×R₂×cos(−λ−π/2)−sin θ×R₂×sin(−λ−π/2), sin θ×R₂×cos(−λ−π/2)+cosθ×R₂×sin(−λ−π/2))

Coordinates on an I-Q plane of the constellation point 4-1 [1000]: (cosθ×R₃×cos(3π/4)−sin θ×R₃×sin(3π/4), sin θ×R₃×cos(3π/4)+cosθ×R₃×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 4-2 [1001]: (cosθ×R₂×cos(π−λ)−sin θ×R₂×sin(π−λ), sin θ×R₂×cos(π−λ)+cos θ×R₂×sin(π−λ))

Coordinates on an I-Q plane of the constellation point 4-3 [1101]: (cosθ×R₂×cos(−π+λ)−sin θ×R₂×sin(−π+λ), sin θ×R₂×cos(−π+λ)+cosθ×R₂×sin(−π+λ))

Coordinates on an I-Q plane of the constellation point 4-4 [1100]: (cosθ×R₃×cos(−3π/4)−sin θ×R₃×sin(−3π/4), sin θ×R₃×cos(−3π/4)+cos θ×R₃sin(−3π/4))

With respect to phase, the unit used is radians. Accordingly, anin-phase component I_(n) and a quadrature component Q_(n) of a basebandsignal after normalization is represented as below.

Coordinates on an I-Q plane of the constellation point 1-1 [0000]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₃×cos(π/4)−a_((4,8,4))×sin θ×R₃sin(π/4), a_((4,8,4))×sin θ×R₃×cos(π/4)+a_((4,8,4))×cos θ×R₃×sin(π/4))

Coordinates on an I-Q plane of the constellation point 1-2 [0001]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos λ−a_((4,8,4))×sin θR₂×sin λ,a_((4,8,4)) sin θ×R₂×cos λ+a_((4,8,4))×cos R₂×sin λ)

Coordinates on an I-Q plane of the constellation point 1-3 [0101]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(−λ)−a_((4,8,4))×sinθ×R₂×sin(−λ), a_((4,8,4))×sin θ×R₂×cos(−λ)+a_((4,8,4))×cos θ×R₂×sin(−λ))

Coordinates on an I-Q plane of the constellation point 1-4 [0100]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₃×cos(−π/4)−a_((4,8,4)) sinθ×R₃×sin(−π/4), a_((4,8,4))×sin θ×R₃×cos(−7π/4)+a_((4,8,4))×cosθ×R₃×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 2-1 [0010]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(−λ+π/2)−a_((4,8,4)) sinθ×R₂×sin(−λ+π/2), a_((4,8,4))×sin θ×R₂×cos(−λ+π/2)+a_((4,8,4))×cosθ×R₂×sin(−λ+π/2))

Coordinates on an I-Q plane of the constellation point 2-2 [0011]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₁×cos(π/4)−a_((4,8,4)) sinθ×R₁×sin(π/4), a_((4,8,4))×sin θ×R₁×cos(π/4)+a_((4,8,4))×cosθ×R₁×sin(π/4))

Coordinates on an I-Q plane of the constellation point 2-3 [0111]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₁×cos(−π/4)−a_((4,8,4)) sinθ×R₁×sin(−π/4), a_((4,8,4))×sin θ×R₁×cos(−π/4)+a_((4,8,4))×cosθ×R₁×sin(−π/4))

Coordinates on an I-Q plane of the constellation point 2-4 [0110]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(λ−π/2)−a_((4,8,4))×sinθ×R₂×sin(λ−π/2), a_((4,8,4))×sin θ×R₂ cos(λ−π/2)+a_((4,8,4))×cosθ×R₂×sin(λ−π/2))

Coordinates on an I-Q plane of the constellation point 3-1 [1010]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(λ+π/2)−a_((4,8,4))×sinθ×R₂×sin(λ+π/2), a_((4,8,4))×sin θ×R₂×cos(λ+π/2)+a_((4,8,4))×cosθ×R₂×sin(λ+π/2))

Coordinates on an I-Q plane of the constellation point 3-2 [1011]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₁×cos(3π/4)−a_((4,8,4))×sinθ×R₁×sin(3π/4), a_((4,8,4)) sin θ×R₁×cos(3π/4)+a_((4,8,4))×cosθ×R₁×sin(3π/4))

Coordinates on an I-Q plane of the constellation point 3-3 [1111]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₁×cos(−3π/4)−a_((4,8,4)) sinθ×R₁×sin(−3π/4), a_((4,8,4)) sin θ×R₁×cos(−3π/4)+a_((4,8,4))×cosθ×R₁×sin(−3π/4))

Coordinates on an I-Q plane of the constellation point 3-4 [1110]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(−λ−7π/2)−a_((4,8,4)) sinθ×R₂×sin(−λ−π/2), a_((4,8,4))×sin θ×R₂×cos(−λ−π/2)+a_((4,8,4))×cosθ×R₂×sin(−λ−π/2))

Coordinates on an I-Q plane of the constellation point 4-1 [1000]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₃×cos(3π/4)−a_((4,8,4))×sin θ×R₃sin(3π/4), a_((4,8,4))×sin θ×R₃×cos(3π/4)+a_((4,8,4))×cos θ×R₃sin(3π/4))

Coordinates on an I-Q plane of the constellation point 4-2 [1001]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(π−λ)−a_((4,8,4))×sinθ×R₂×sin(−λ), a_((4,8,4)) sin θ×R₂ cos(π−λ)+a_((4,8,4))×cosθ×R₂×sin(π−λ))

Coordinates on an I-Q plane of the constellation point 4-3 [1101]:(I_(n), Q_(n))=(a_((4,8,4))×cos θ×R₂×cos(−π+λ)−a_((4,8,4))×sinθ×R₂×sin(−π+λ), a_((4,8,4))×sin θ×R₂×cos(−π+λ)+a_((4,8,4))×cosθ×R₂×sin(−π+λ))

Coordinates on an I-Q plane of the constellation point 4-4 [1100]:(I_(n), Q_(n))=(a_((4,8,4))×cos R₃×cos(−3π/4)−a_((4,8,4)) sin θ×R₃sin(−3π/4), a_((4,8,4))×sin θ×R₃×cos(−3π/4)+a_((4,8,4))×cosθ×R₃×sin(−3π/4))

Note that θ is a phase provided on an in-phase (I)-quadrature-phase (Q)plane, and a_((4,8,4)) is as shown in Math (26).

When forming a symbol by (4,8,4)16APSK, as above, and (12,4)16APSK, andwhen implemented similarly to embodiment 1, any of the followingtransmission methods may be considered.

-   -   In a symbol group of at least three consecutive symbols (or at        least four consecutive symbols), among which a modulation scheme        for each symbol is (12,4)16APSK or (4,8,4)16APSK, there are no        consecutive (12,4)16APSK symbols and there are no consecutive        (4,8,4)16APSK symbols”.    -   In a “symbol group of period (cycle) M”, the number of        (4,8,4)16APSK symbols is one greater than the number of        (12,4)16APSK symbols, in other words the number of (12,4)16APSK        symbols is N and the number of (4,8,4)16APSK symbols is N+1.        Note that N is a natural number. Thus, in a “symbol group of        period (cycle) M”, there are no consecutive (4,8,4)16APSK        symbols or there is only 1 position at which two consecutive        (4,8,4)16APSK symbols exist. Accordingly, three or more        consecutive (4,8,4)16APSK symbols do not exist.    -   When each data symbol is either a (12,4)16APSK symbol or a        (4,8,4)16APSK symbol, three or more consecutive (4,8,4)16APSK        symbols are not present in a consecutive data symbol group.

Thus, by replacing description related to (8,8)16APSK symbols with(4,8,4)16APSK for portions of embodiment 1 to embodiment 4 in which(12,4)16APSK symbols and (8,8)16APSK symbols are described (for example,transmission method, pilot symbol configuration method (embodiment 2),receive apparatus configuration, control information configurationincluding TMCC, etc.), a transmission method using (12,4)16APSK symbolsand (4,8,4)16APSK can be implemented in the same way as described inembodiment 1 to embodiment 4.

Embodiment 9

In embodiment 8, a case is described in which (4,8,4)16APSK symbols areused instead of the (8,8)16APSK symbols in embodiment 1 to embodiment 4.In the present embodiment, conditions are described related toconstellations for improving data reception quality with respect to the(4,8,4)16APSK described in embodiment 8.

As stated in embodiment 8, FIG. 30 illustrates an example arrangement of16 constellation points of (4,8,4)16APSK in an in-phase(I)-quadrature-phase (Q) plane. Here, phases forming a half-line of Q=0and I≧0 and a half-line of Q=(tan λ)×I and Q≧0 are considered to be λ(radians) (0 radians <λ<π/4 radians).

In FIG. 30, 16 constellation points of (4,8,4)16APSK are drawn so thatλ<π/8 radians.

In FIG. 31, 16 constellation points of (4,8,4)16APSK are drawn so thatλ≧π/8 radians.

First, eight constellation points, i.e. constellation point 1-2,constellation point 1-3, constellation point 2-1, constellation point2-4, constellation point 3-1, constellation point 3-4, constellationpoint 4-2, and constellation point 4-3 exist on an intermediate size“mid circle” of radius R₂. Focusing on these eight constellation points,a method of setting λ to π/8 radians, as in a constellation of 8PSK, maybe considered in order to achieve high reception quality.

However, four constellation points, i.e., constellation point 1-1,constellation point 1-4, constellation point 4-1, and constellationpoint 4-4 exist on a largest “outer circle” of radius R₃. Further, fourconstellation points, i.e., constellation point 2-2, constellation point2-3, constellation point 3-2, and constellation point 3-3, exist on asmallest “inner circle” of radius R₁. When focusing on the relationshipbetween these constellation points and the eight constellation points onthe “mid circle”, <Condition 9> is preferably satisfied (Condition 9becomes a condition for achieving high data reception quality).

<Condition 9>

λ<π/8 radians

This point is described with reference to FIG. 30 and FIG. 31. In FIG.30 and FIG. 31, constellation point 1-2 and constellation point 2-1 onthe “mid circle”, constellation point 1-1 on the “outer circle”, andconstellation point 2-2 on the “inner circle”, all in a first quadrant,are focused on. Although constellation point 1-2, constellation point2-1, constellation point 1-1, and constellation point 2-2 in the firstquadrant are focused on, discussion focusing on these four constellationpoints also applies to four constellation points in a second quadrant,four constellation points in a third quadrant, and four constellationpoints in a fourth quadrant.

As can be seen from FIG. 31, when λ≧π/8, a distance betweenconstellation point 1-2 and constellation point 2-1 on the “mid circle”and constellation point 1-1 on the “outer circle” becomes short. Thus,because resistance to noise is reduced, data reception quality by areceive apparatus decreases.

In the case of FIG. 31, constellation point 1-1 on the “outer circle” isfocused on, but according to values of R₁, R₂, and R₃, focus onconstellation point 2-2 on the “inner circle” may be required, so thatwhen λ≧π/8 radians, a distance between constellation point 1-2 andconstellation point 2-1 on the “mid circle” and constellation point 2-2on the “inner circle” becomes short. Thus, because resistance to noiseis reduced, data reception quality by a receive apparatus decreases.

On the other hand, when λ<π/8 radians is set as in FIG. 30, a distancebetween constellation point 1-1 and constellation point 1-2, a distancebetween constellation point 1-1 and constellation point 2-1, a distancebetween constellation point 2-2 and constellation point 1-2, and adistance between constellation point 2-2 and constellation point 2-1 canall be set larger, which is one condition for achieving high datareception quality.

From the above points, <Condition 9> becomes an important condition fora receive apparatus to achieve high data reception quality.

The following describes further conditions for a receive apparatus toachieve high data reception quality.

In FIG. 32, constellation point 1-2 and constellation point 2-2 of thefirst quadrant are focused on. Although constellation point 1-2 andconstellation point 2-2 of the first quadrant are focused on here, thisfocus is also applicable to constellation point 3-2 and constellationpoint 4-2 of the second quadrant, constellation point 3-3 andconstellation point 4-3 of the third quadrant, and constellation point1-3 and constellation point 2-3 of the fourth quadrant.

Coordinates of constellation point 1-2 are (R₂ cos λ,R₂ sin λ), andcoordinates of constellation point 2-2 are (R₁ cos(π/4),R₁ sin(π/4)). Inorder to increase the probability of a receive apparatus achieving ahigh data reception quality, the following condition is provided.

<Condition 10>

R₁ sin(π/4)<R₂ sin λ

Among the four constellation points on the “inner circle”, the smallestEuclidean distance is α. (Euclidean distance between constellation point2-2 and constellation point 2-3, Euclidean distance betweenconstellation point 2-3 and constellation point 3-3, and Euclideandistance between constellation point 3-2 and constellation point 2-2 isα.)

Among the eight constellation points on the “mid circle”, a Euclideandistance between constellation point 1-2 and constellation point 1-3 isβ. Distance between constellation point 2-1 and constellation point 3-1,distance between constellation point 4-2 and constellation point 4-3,and distance between constellation point 3-4 and constellation point 2-4is also β.

When <Condition 10> is satisfied, α<β holds true.

Considering the points above, when both <Condition 9> and <Condition 10>are satisfied, and when Euclidean distance derived by extracting twodifferent constellation points among 16 constellation points isconsidered, regardless of which two constellation points are extracted,the Euclidean distance is large, and therefore the possibility of areceive apparatus achieving high data reception quality is increased.

However, there is the possibility of a receive apparatus achieving highdata reception quality without satisfying <Condition 9> and/or<Condition 10>. This is because there is the possibility of differentsuitable conditions existing according to distortion characteristics(for example, see FIG. 1) of a power amplifier for transmission includedin the radio section 712 of the transmit apparatus illustrated in FIG.7.

In this case, when considering arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as disclosed in embodiment 8, thefollowing condition is added in addition to <Condition 10>

Coordinates of constellation point 1-2 are (R₂ cos λ,R₂×sin λ), andcoordinates of constellation point 2-2 are (R₁ cos(π/4),R₁ sin(π/4)).Thus, the following condition is provided.

<Condition 11>

R₁ sin(π/4)≠R₂×sin λ

Coordinates of constellation point 1-1 are (R₃ cos(π/4),R₃ sin(π/4)),and coordinates of constellation point 1-2 are (R₂ cos λ,R₂×sin λ).Thus, the following condition is provided.

<Condition 12>

R₂ cos λ≠R₃ cos(π/4)

Thus, the following nine (4,8,4)16APSK are considered.

[1] Satisfying <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[2] Satisfying <Condition 11> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[3] Satisfying <Condition 12> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[4] Satisfying <Condition 9> and <Condition 10> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[5] Satisfying <Condition 9> and <Condition 11> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[6] Satisfying <Condition 9> and <Condition 12> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[7] Satisfying <Condition 10> and λ=π/12 for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[8] Satisfying <Condition 11> and λ=π/12 for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[9] Satisfying <Condition 12> and λ=π/12 for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

Constellations (coordinates of constellation points) on an in-phase(I)-quadrature-phase (Q) plane of these nine (4,8,4)16APSK schemes aredifferent from constellations (coordinates of constellation points) onan in-phase (I)-quadrature-phase (Q) plane of the NU-16QAM schemedescribed in embodiment 7, and are constellations characteristic of thepresent embodiment.

Further, the following nine (4,8,4)16APSK are considered.

[10] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 10> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[11] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 11> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[12] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 12> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[13] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[14] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 11> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[15] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 12> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[16] Satisfying <Condition 7> and <Condition 8>, λ=π/12 radians, andsatisfying <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[17] Satisfying <Condition 7> and <Condition 8>, λ=π/12 radians, andsatisfying <Condition 11> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[18] Satisfying <Condition 7>, and <Condition 8>, λ=π/12 radians, andsatisfying <Condition 12> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

According to the above, the number of different bits of labelling amongconstellation points that are near each other in an in-phase(I)-quadrature-phase (Q) plane is low, and therefore the possibility ofa receive apparatus achieving high data reception quality is increased.Thus, when a receive apparatus performs iterative detection, thepossibility of the receive apparatus achieving high data receptionquality is increased.

Embodiment 10

According to embodiment 1 to embodiment 4, methods of switching(12,4)16APSK symbols and (8,8)16APSK symbols in a transmit frame,methods of configuring pilot symbols, methods of configuring controlinformation including TMCC, etc., have been described. Embodiment 7describes a method using NU-16QAM instead of (8,8)16APSK as described inembodiment 1 to embodiment 4, and embodiment 8 describes a method using(4,8,4)16APSK instead of (8,8)16APSK as described in embodiment 1 toembodiment 4.

In embodiment 9, a constellation of (4,8,4)16APSK is described for areceive apparatus to achieve improved data reception quality in a methodusing (4,8,4)16APSK instead of the (8,8)16APSK described in embodiment 1to embodiment 4.

For example, in a situation in which distortion characteristics aresevere, such as satellite broadcasting by using a power amplifier fortransmission included in the radio section 712 of the transmit apparatusillustrated in FIG. 7, even when (only) using (4,8,4)16APSK as amodulation scheme, PAPR is low and therefore intersymbol interference isreduced and, when compared to (12,4)16APSK, (4,8,4)16APSK improvesconstellation and labelling, and therefore a receive apparatus is likelyto achieve high data reception quality.

In the present embodiment, this point, i.e., a transmission method thatcan specify (4,8,4)16APSK as a modulation scheme of data symbols isdescribed.

For example, in a frame of a modulated signal such as in FIG. 11,(4,8,4)16APSK can be specified as a modulation scheme of Data #1 to Data#7920.

Accordingly, in FIG. 11, when “1st symbol, 2nd symbol, 3rd symbol, . . ., 135th symbol, 136th symbol” are arranged along a horizontal axis oftime, (4,8,4)16APSK can be specified as the modulation scheme of “1stsymbol, 2nd symbol, 3rd symbol, . . . , 135th symbol, 136th symbol”.

As one feature of such configuration, “two or more (4,8,4)16APSK symbolsare consecutive”. Two or more consecutive (4,8,4)16APSK symbols areconsecutive along a time axis when, for example, a single carriertransmission scheme is used (see FIG. 33). Further, when a multi-carriertransmission scheme such as orthogonal frequency division multiplexing(OFDM) is used, the two or more consecutive (4,8,4)16APSK symbols may beconsecutive along a time axis (see FIG. 33), and may be consecutivealong a frequency axis (see FIG. 34).

FIG. 33 illustrates an example arrangement of symbols when time is ahorizontal axis. A (4,8,4)16APSK symbol at time #1, a (4,8,4)16APSKsymbol at time #2, a (4,8,4)16APSK symbol at time #3, . . . .

FIG. 34 illustrates an example arrangement of symbols when frequency isa horizontal axis. A (4,8,4)16APSK symbol at carrier #1, a (4,8,4)16APSKsymbol at carrier #2, a (4,8,4)16APSK symbol at carrier #3, . . . .

Further examples of “two or more (4,8,4)16APSK symbols are consecutive”are illustrated in FIG. 35 and FIG. 36.

FIG. 35 illustrates an example arrangement of symbols when time is ahorizontal axis. Another symbol at time #1, a (4,8,4)16APSK symbol attime #2, a (4,8,4)16APSK symbol at time #3, a (4,8,4)16APSK symbol attime #4, another symbol at time #5, . . . . The other symbol may be apilot symbol, a symbol transmitting control information, a referencesymbol, a symbol for frequency or time synchronization, or any kind ofsymbol.

FIG. 36 illustrates an example arrangement of symbols when frequency isa horizontal axis. Another symbol at carrier #1, a (4,8,4)16APSK symbolat carrier #2, a (4,8,4)16APSK symbol at carrier #3, a (4,8,4)16APSKsymbol at carrier #4, another symbol at carrier #5, . . . . The othersymbol may be a pilot symbol, a symbol transmitting control information,a reference symbol, a symbol for frequency or time synchronization, orany kind of symbol.

(4,8,4)16APSK symbols may be symbols for transmitting data and may bepilot symbols as described in embodiment 2.

When a (4,8,4)16APSK symbol is a symbol for transmitting data,(4,8,4)16APSK mapping described in embodiment 8 is performed to obtainan in-phase component and quadrature component of a baseband signal fromfour bits of data, b₃, b₂, b₁, and b₀.

As above, when a modulation scheme of a data symbol is (4,8,4)16APSK,PAPR is low and therefore occurrence of intersymbol interference isreduced and, when compared to (12,4)16APSK, (4,8,4)16APSK is preferredfor constellation and labelling, and therefore a receive apparatus islikely to achieve high data reception quality.

In this case, when the constellation described in embodiment 9 isapplied to (4,8,4)16APSK, the probability of achieving higher datareception quality becomes higher. Specific examples are as follows.

[1] Satisfying <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[2] Satisfying <Condition 11> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[3] Satisfying <Condition 12> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[4] Satisfying <Condition 9> and <Condition 10> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[5] Satisfying <Condition 9> and <Condition 11> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[6] Satisfying <Condition 9> and <Condition 12> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[7] Satisfying <Condition 10> and λ=π/12 radians for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[8] Satisfying <Condition 11> and λ=π/12 radians for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[9] Satisfying <Condition 12> and λ=π/12 radians for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[10] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 10> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[11] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 11> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[12] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 12> for arrangement of constellation points (coordinates ofconstellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[13] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[14] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 11> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[15] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 12> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

[16] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 10> and λ=π/12 radians for arrangement of constellationpoints (coordinates of constellation points) of (4,8,4)16APSK on anin-phase (I)-quadrature-phase (Q) plane as described in embodiment 8.(R₁<R₂<R₃)

[17] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 11> and λ=π/12 radians for arrangement of constellationpoints (coordinates of constellation points) of (4,8,4)16APSK on anin-phase (I)-quadrature-phase (Q) plane as described in embodiment 8.(R₁<R₂<R₃)

[18] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 12> and λ=π/12 radians for arrangement of constellationpoints (coordinates of constellation points) of (4,8,4)16APSK on anin-phase (I)-quadrature-phase (Q) plane as described in embodiment 8.(R₁<R₂<R₃)

[19] Satisfying <Condition 9> and <Condition 10> for arrangement ofconstellation points (coordinates of constellation points) of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane as describedin embodiment 8. (R₁<R₂<R₃)

[20] Satisfying <Condition 7> and <Condition 8>, and satisfying<Condition 9> and <Condition 10> for arrangement of constellation points(coordinates of constellation points) of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane as described in embodiment 8. (R₁<R₂<R₃)

Embodiment 11 Example of Pilot Symbols

In the present embodiment, an example of pilot symbol configuration isdescribed in the transmission scheme described in embodiment 10 (themodulation scheme of data symbols is (4,8,4)16APSK).

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here. However, (4,8,4)16APSK is usedinstead of (8,8)16APSK.

Intersymbol interference occurs for modulated signals because ofnon-linearity of the power amplifier of the transmit apparatus. Highdata reception quality can be achieved by a receive apparatus bydecreasing this intersymbol interference.

In the present example of pilot symbol configuration, in order to reduceintersymbol interference at a receive apparatus, when data symbols areconfigured so that “two or more (4,8,4)16APSK symbols are consecutive”,a transmit apparatus generates and transmits, as pilot symbols, allbaseband signals corresponding to all possible constellation points of(4,8,4)16APSK on an in-phase (I)-quadrature-phase (Q) plane (in otherwords, baseband signals corresponding to 16 constellation points of fourtransmit bits [b₃b₂b₁b₀], from [0000] to [1111]). Thus, a receiveapparatus can estimate intersymbol interference for all possibleconstellation points of (4,8,4)16APSK on an in-phase(I)-quadrature-phase (Q) plane, and therefore achieving high datareception quality is likely.

Specifically, the following are transmitted as pilot symbols (referencesymbols), in order:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (4,8,4)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (4,8,4)16APSK.

The above feature means that:

<1> Symbols corresponding to all constellation points of (4,8,4)16APSKon an in-phase (I)-quadrature-phase (Q) plane, i.e., the followingsymbols, are transmitted in any order:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (4,8,4)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (4,8,4)16APSK.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset usingthe pilot symbols.

Further, a transmission method of pilot symbols is not limited to theabove. Above, the pilot symbols are configured as 16 symbols, but when,for example, the pilot symbols are configured as 16×N symbols (N being anatural number), there is an advantage that the number of occurrences ofeach of the following symbols can be equalized:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (4,8,4)16APSK;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (4,8,4)16APSK; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (4,8,4)16APSK.

Embodiment 12 Signaling

In the present embodiment, examples are described of various informationsignaled as TMCC information in order to facilitate reception at thereceive apparatus of a transmit signal used in the transmission schemedescribed in embodiment 10.

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here. However, (4,8,4)16APSK is usedinstead of (8,8)16APSK.

FIG. 18 illustrates a schematic of a frame of a transmit signal ofadvanced wide band digital satellite broadcasting (however, FIG. 18 isnot intended to be an exact illustration of a frame of advanced wideband digital satellite broadcasting). Note that details are described inembodiment 3, and therefore description is omitted here.

Table 9 illustrates a configuration of modulation scheme information. Intable 9, for example, when four bits to be transmitted by a symbol fortransmitting a modulation scheme of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0001],a modulation scheme for generating symbols of “slots composed of asymbol group” is π/2 shift binary phase shift keying (BPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0010], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is quadrature phase shift keying (QPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0011], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 8 phase shift keying (8PSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0100], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (12,4)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0101], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (4,8,4)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0110], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 32 amplitude phase shift keying (32APSK).

TABLE 9 Modulation scheme information Value Assignment 0000 Reserved0001 π/2 shift BPSK 0010 QPSK 0011 8PSK 0100 (12, 4)16APSK 0101 (4, 8,4)16APSK 0110 32APSK 0111 . . . . . . . . . 1111 No scheme assigned

Table 10 illustrates a relationship between coding rates of errorcorrection code and ring ratios when a modulation scheme is(12,4)16APSK. According to R₁ and R₂, used above to representconstellation points in an I-Q plane of (12,4)16APSK, a ring ratioR_((12,4)) of (12,4)16APSK is represented as R_((12,4))=R₂/R₁. In Table10, for example, when four bits to be transmitted by a symbol fortransmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen a symbol for transmitting a modulation scheme of a transmissionmode is indicated to be (12,4)16APSK, a ring ratio R_((12,4)) of(12,4)16APSK is 3.09.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 2.97.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 3.93.

. . .

TABLE 10 Relationship between coding rates of error correction code andring ratios when modulation scheme is (12, 4)16APSK Coding rate RingValue (approximate value) ratio 0000 41/120 (1/3) 3.09 0001 49/120 (2/5)2.97 0010 61/120 (1/2) 3.93 . . . . . . . . . 1111 No scheme assigned —

Table 11 indicates a relationship between coding rate of errorcorrection code and radii/phases, when a modulation scheme is(4,8,4)16APSK.

In Table 11, for example, when four bits to be transmitted by a symbolfor transmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen a symbol for transmitting a modulation scheme of a transmissionmode is indicated to be (4,8,4)16APSK, R₁=1.00, R₂=2.00, R₃=2.20, andphase λ=π/12 radians.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (4,8,4)16APSK, R₁=1.00, R₂=2.10, R₃=2.20, and phase λ=π/12 radians.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (4,8,4)16APSK, R₁=1.00, R₂=2.20, R₃=2.30, and phase λ=π/10 radians.

. . .

TABLE 11 Relationship between radii/phases of error correction codingand ring ratios when modulation scheme is (4, 8, 4)16APSK Coding rateValue (approximate value) Radii and phase 0000 41/120 (1/3) R₁ = 1.00,R₂ = 2.00, R₃ = 2.20, λ = π/12 0001 49/120 (2/5) R₁ = 1.00, R₂ = 2.10,R₃ = 2.20, λ = π/12 0010 61/120 (1/2) R₁ = 1.00, R₂ = 2.20, R₃ = 2.30, λ= π/10 . . . . . . . . . 1111 No scheme assigned —

<Receive Apparatus>

The following describes operation of a receive apparatus that receives aradio signal transmitted by the transmit apparatus 700, with referenceto the diagram of a receive apparatus in FIG. 19.

The receive apparatus 1900 of FIG. 19 receives a radio signaltransmitted by the transmit apparatus 700 via the antenna 1901. The RFreceiver 1902 performs processing such as frequency conversion andquadrature demodulation on a received radio signal, and outputs abaseband signal.

The demodulator 1904 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

The synchronization and channel estimator 1914 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

The control information estimator 1916 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal.

Of importance in the present embodiment is that a receive apparatusdemodulates and decodes a symbol transmitting “transmission modemodulation scheme” information and a symbol transmitting “transmissionmode coding rate” of “transmission mode/slot information” of a “TMCCinformation symbol group”; and, based on Table 9, Table 10, and Table11, the control information estimator 1916 generates modulation schemeinformation and error correction code scheme (for example, coding rateof error correction code) information used by “slots composed of a datasymbol group”, and generates ring ratio and radii/phase information whena modulation scheme used by “slots composed of a data symbol group” is(12,4)16APSK, (4,8,4)16APSK, or 32APSK, and outputs the information as aportion of a control signal.

The de-mapper 1906 receives a post-filter baseband signal, controlsignal, and estimated signal as input, determines a modulation scheme(or transmission method) used by “slots composed of a data symbol group”based on the control signal (in this case, when there is a ring ratioand radii/phase, determination with respect to the ring ratio andradii/phase is also performed), calculates, based on this determination,a log-likelihood ratio (LLR) for each bit included in a data symbol fromthe post-filter baseband signal and estimated signal, and outputs thelog-likelihood ratios. (However, instead of a soft decision value suchas an LLR a hard decision value may be outputted, and a soft decisionvalue instead of an LLR may be outputted.)

The de-interleaver 1908 receives log-likelihood ratios as input,accumulates input, performs de-interleaving (permutes data)corresponding to interleaving used by the transmit apparatus, andoutputs post-de-interleaving log-likelihood ratios.

The error correction decoder 1912 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection code used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method.

The above describes operation when iterative detection is not performed.The following is supplemental description of operation when iterativedetection is performed. Note that a receive apparatus need not implementiterative detection, and a receive apparatus may be a receive apparatusthat performs initial detection and error detection decoding withoutbeing provided with elements related to iterative detection that aredescribed below.

When iterative detection is performed, the error correction decoder 1912outputs a log-likelihood ratio for each post-decoding bit (note thatwhen only initial detection is performed, output of a log-likelihoodratio for each post decoding bit is not necessary).

The interleaver 1910 interleaves log-likelihood ratios of post-decodingbits (performs permutation), and outputs post-interleavinglog-likelihood ratios.

The de-mapper 1906 performs iterative detection by usingpost-interleaving log-likelihood ratios, a post-filter baseband signal,and an estimated signal, and outputs a log-likelihood ratio for eachpost-iterative detection bit.

Subsequently, interleaving and error correction code operations areperformed. Thus, these operations are iteratively performed. In thisway, finally the possibility of achieving a preferable decoding resultis increased.

In the above description, a feature thereof is that by a receptionapparatus obtaining a symbol for transmitting a modulation scheme of atransmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group” and a symbol for transmitting a coding rate ofa transmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group”, a modulation scheme and coding rate of errordetection coding are estimated, and, when a modulation scheme is 16APSK,32APSK, ring ratios and radii/phases are estimated, and demodulation anddecoding operations become possible.

The above description describes the frame configuration in FIG. 18, butframe configurations applicable to the present invention are not limitedin this way. When a plurality of data symbols exist, a symbol exists fortransmitting information related to a modulation scheme used ingenerating the plurality of data symbols, and a symbol exists fortransmitting information related to an error correction scheme (forexample, error correction code used, code length of error correctioncode, coding rate of error correction code, etc.) used in generating theplurality of data symbols, any arrangement in a frame may be used withrespect to the plurality of data symbols, the symbol for transmittinginformation related to a modulation scheme, and the symbol fortransmitting information related to an error correction scheme. Further,symbols other than these symbols, for example a symbol for preamble andsynchronization, pilot symbols, a reference symbol, etc., may exist in aframe.

In addition, as a method different to that described above, a symboltransmitting information related to ring ratios and radii/phases mayexist, and the transmit apparatus may transmit the symbol. An example ofa symbol transmitting information related to ring ratios andradii/phases is illustrated below.

TABLE 12 Example of symbol transmitting information related to ringratios and radii/phases Value Assignment 00000 (12, 4)16APSK ring ratio4.00 00001 (12, 4)16APSK ring ratio 4.10 00010 (12, 4)16APSK ring ratio4.20 00011 (12, 4)16APSK ring ratio 4.30 00100 (4, 8, 4)16APSK R₁ =1.00, R₂ = 2.00, R₃ = 2.20, λ = π/12 00101 (4, 8, 4)16APSK R₁ = 1.00, R₂= 2.10, R₃ = 2.20, λ = π/12 00110 (4, 8, 4)16APSK R₁ = 1.00, R₂ = 2.20,R₃ = 2.30, λ = π/10 00111 (4, 8, 4)16APSK R₁ = 1.00, R₂ = 2.20, R₃ =2.30, λ = π/12 . . . . . . 11111 . . .

In Table 12, when [00000] is transmitted by a symbol transmittinginformation related to ring ratio and radii/phase, a data symbol is asymbol of “(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.10”.

When [00010] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.20”.

When [00011] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.30”.

When [00100] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.00, R₃=2.20, λ=π/12”.

When [00101] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.10, R₃=2.20, λ=π/12”.

When [00110] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.20, R₃=2.30, λ=π/10”.

When [00111] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.20, R₃=2.30, λ=7π/12”.

Thus, by obtaining a symbol transmitting information related to ringratio and radii/phases, a receive apparatus can estimate a ring ratioand radii/phases used by a data symbol, and therefore demodulation anddecoding of the data symbol becomes possible.

Further, ring ratio and radii/phases information may be included in asymbol for transmitting a modulation scheme. An example is illustratedbelow.

TABLE 13 Modulation scheme information Value Assignment 00000 (12,4)16APSK ring ratio 4.00 00001 (12, 4)16APSK ring ratio 4.10 00010 (12,4)16APSK ring ratio 4.20 00011 (12, 4)16APSK ring ratio 4.30 00100 (4,8, 4)16APSK R₁ = 1.00, R₂ = 2.00, R₃ = 2.20, λ = π/12 00101 (4, 8,4)16APSK R₁ = 1.00, R₂ = 2.10, R₃ = 2.20, λ = π/12 00110 (4, 8, 4)16APSKR₁ = 1.00, R₂ = 2.20, R₃ = 2.30, λ = π/10 00111 (4, 8, 4)16APSK R₁ =1.00, R₂ = 2.20, R₃ = 2.30, λ = π/12 . . . . . . 11101 8PSK 11110 QPSK11111 π/2 shift BPSK

In Table 13, when [00000] is transmitted by a symbol transmittingmodulation scheme information, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10”.

When [00010] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.20”.

When [00011] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.30”.

When [00100] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.00, R₃=2.20, λ=π/12”.

When [00101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.10, R₃=2.20, λ=π/12”.

When [00110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.20, R₃=2.30, λ=π/10”.

When [00111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.20, R₃=2.30, λ=π/12”.

When [11101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “8PSK”.

When [11110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “QPSK”.

When [11111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “π/2 shift BPSK”.

Thus, by obtaining a symbol transmitting modulation scheme information,a receive apparatus can estimate a modulation scheme, ring ratio, radii,and phases used by a data symbol, and therefore demodulation anddecoding of the data symbol becomes possible.

Note that in the above description, examples are described including“(12,4)16APSK” and “(4,8,4)16APSK” as selectable modulation schemes(transmission methods), but modulation schemes (transmission methods)are not limited to these examples. In other words, other modulationschemes may be selectable.

Embodiment 13

In the present embodiment, an order of generation of a data symbol isdescribed.

FIG. 18, part (a) illustrates a schematic of a frame configuration. InFIG. 18, part (a), the “#1 symbol group”, the “#2 symbol group”, the “#3symbol group”, . . . are lined up. Each symbol group among the “#1symbol group”, the “#2 symbol group”, the “#3 symbol group”, . . . isherein composed of a “synchronization symbol group”, a “pilot symbolgroup”, a “TMCC information symbol group”, and “slots composed of a datasymbol group”, as illustrated in FIG. 18, part (a).

Here, a configuration scheme is described of data symbol groups in each“slots composed of a data symbol group” among, for example, N symbolgroups including the “#1 symbol group”, the “#2 symbol group”, the “#3symbol group”, . . . , an “#N−1 symbol group”, an “#N symbol group”.

A rule is provided with respect to generation of data symbol groups ineach “slots composed of a data symbol group” among N symbol groups froma “#(β×N+1) symbol group” to a “#(β×N+N) symbol group”. The rule isdescribed with reference to FIG. 37.

Thus, a data symbol group of (4,8,4)16APSK of FIG. 37 satisfies featuresof FIG. 37, part (a), to FIG. 37, part (f). Note that in FIG. 37, thehorizontal axis is symbols.

FIG. 37, part (a):

When a 32APSK data symbol exists and a (12,4)16APSK data symbol does notexist, a “(4,8,4)16APSK data symbol” exists after a “32APSK datasymbol”, as illustrated in FIG. 37, part (a).

FIG. 37, part (b):

When a (12,4)16APSK data symbol exists, a “(4,8,4)16APSK data symbol”exists after a “(12,4)16APSK data symbol”, as illustrated in FIG. 37,part (b).

FIG. 37, part (c):

When a (12,4)16APSK data symbol exists, a “(12,4)16APSK data symbol”exists after a “(4,8,4)16APSK data symbol”, as illustrated in FIG. 37,part (b).

Either FIG. 37, part (b), or FIG. 37, part (c) may be satisfied.

FIG. 37, part (d):

When an 8PSK data symbol exists and a (12,4)16APSK data symbol does notexist, an “8PSK data symbol” exists after a “(4,8,4)16APSK data symbol”,as illustrated in FIG. 37, part (d).

FIG. 37, part (e):

When an QPSK data symbol exists, an 8PSK data symbol does not exist, anda (12,4)16APSK data symbol does not exist, a “QPSK data symbol” existsafter a “(4,8,4)16APSK data symbol”, as illustrated in FIG. 37, part(e).

FIG. 37, part (f):

When a π/2 shift BPSK data symbol exists, a QPSK data symbol does notexist, an 8PSK data symbol does not exist, and a (12,4)16APSK datasymbol does not exist, a “π/2 shift BPSK data symbol” exists after a“(4,8,4)16APSK data symbol”, as illustrated in FIG. 37, part (f).

When symbols are arranged as described above, there is an advantage thata receive apparatus can easily perform automatic gain control (AGC)because a signal sequence is arranged in order of modulation schemes(transmission methods) of high peak power.

FIG. 38 illustrates an example configuration method of the“(4,8,4)16APSK data symbol” described above.

Assume that a “(4,8,4)16APSK data symbol” of a coding rate X of errorcorrection code and a “(4,8,4)16APSK data symbol” of a coding rate Y oferror correction code exist. Also assume that a relationship X>Y issatisfied.

Thus, a “(4,8,4)16APSK data symbol” of a coding rate Y of errorcorrection code is arranged after a “(4,8,4)16APSK data symbol” of acoding rate X of error correction code.

As in FIG. 38, assume that a “(4,8,4)16APSK data symbol” of a codingrate 1/2 of error correction code, a “(4,8,4)16APSK data symbol” of acoding rate 2/3 of error correction code, and a “(4,8,4)16APSK datasymbol” of a coding rate 3/4 of error correction code exist. Thus, fromthe above description, as illustrated in FIG. 38, symbols are arrangedin the order of a “(4,8,4)16APSK data symbol” of a coding rate 3/4 oferror correction code, a “(4,8,4)16APSK data symbol” of a coding rate2/3 of error correction code, and a “(4,8,4)16APSK data symbol” of acoding rate 1/2 of error correction code.

Embodiment A

In the present embodiment, a scheme is described that can select a ringratio (for example, a (12,4)16APSK ring ratio) even when a coding rateof error correction code is a given coding rate (for example, codingrate is set to a value K). This scheme contributes to improvements invariation of patterns of switching modulation schemes, for example, andthereby a receive apparatus can achieve high data reception quality bysetting suitable ring ratios.

Note that ring ratio (for example, (12,4)16APSK ring ratio) has beendefined prior to the present embodiment, and ring ratio may also bereferred to as “radius ratio”.

<Transmit Station>

FIG. 39 illustrates an example of a transmit station.

A transmit system A101 in FIG. 39 receives video data and audio data asinput and generates a modulated signal according to a control signalA100.

The control signal A100 specifies code length of error correction code,coding rate, modulation scheme, and ring ratio.

An amplifier A102 receives a modulated signal as input, amplifies themodulated signal, and outputs a post-amplification transmit signal A103.The transmit signal A103 is transmitted via an antenna A104.

<Ring Ratio Selection>

Table 14 illustrates an example of coding rates of error correction codeand ring ratios when a modulation scheme is (12,4)16APSK.

TABLE 14 Coding rates of error correction code and ring ratios whenmodulation scheme is (12, 4)16APSK Coding rate Ring Value (approximatevalue) ratio 0000 41/120 (1/3) 2.99 0001 41/120 (1/3) 3.09 0010 41/120(1/3) 3.19 0011 49/120 (2/5) 2.87 0100 49/120 (2/5) 2.97 0101 49/120(2/5) 3.07 0110 61/120 (1/2) 3.83 . . . . . . . . . 1111 No schemeassigned —

A control signal generator (not illustrated) generates the controlsignal A100 for indicating a value of Table 14 according to a predefinedcoding rate and ring ratio of a transmit apparatus. At the transmitsystem A101, a modulated signal is generated according to a coding rateand ring ratio specified by the control signal A100.

For example, when a transmit apparatus specifies (12,4)16APSK as amodulation scheme, 41/120(≈1/3) as a coding rate of error correctioncode, and 2.99 as a ring ratio, four bits of control information relatedto bit ratio are “0000”. Further, when (12,4)16APSK is specified as amodulation scheme, 41/120(≈1/3) is specified as a coding rate of errorcorrection code, and 3.09 is specified as a ring ratio, four bits ofcontrol information related to bit ratio are “0001”.

Thus, a transmit apparatus transmits “four bits of control informationrelated to ring ratio” as a portion of control information.

Further, at a terminal that receives data (control information)containing four bit values of Table 14 (four bits of control informationrelated to ring ratio), de-mapping (for example, log-likelihood ratiofor each bit) is performed according to a coding rate and ring ratioindicated by the bit values, and data modulation, etc., is performed.

Transmission of this four bit value (four bits of control informationrelated to ring ratio) can be performed using four bits within“transmission mode/slot information” with a “TMCC information symbolgroup”.

Table 14 indicates “in a case in which a symbol for transmitting amodulation scheme of a transmission mode indicates (12,4)16APSK, whenvalues of four bits are “0000”, a coding rate of error correction codefor generating symbols of “slots composed of a data symbol group” is41/120 (≈1/3) and a ring ratio of (12,4)16APSK is R_((12,4))=2.99”.

Further, “in a case in which a symbol for transmitting a modulationscheme of a transmission mode indicates (12,4)16APSK, when values offour bits are “0001”, a coding rate of error correction code forgenerating symbols of “slots composed of a data symbol group” is 41/120(≈1/3) and a ring ratio of (12,4)16APSK is R_((12,4))=3.09”.

Further. “in a case in which a symbol for transmitting a modulationscheme of a transmission mode indicates (12,4)16APSK, when values offour bits are “0010”, a coding rate of error correction code forgenerating symbols of “slots composed of a data symbol group” is 41/120(≈1/3) and a ring ratio of (12,4)16APSK is R_((12,4))=3.19”.

In this Table 14, for each coding rate value three types of ring ratioare assigned, but this is merely one example. In other words, for eachcoding rate value a plurality of types of ring ratio may be assigned.Further, a portion of coding rate values may be assigned one type ofring ratio, and remaining coding rate values may be assigned a pluralityof types of ring ratio.

<Receive Apparatus>

A receive apparatus is described that corresponds to the transmissionmethod of the present embodiment.

A receive apparatus (terminal) A200 of FIG. 40 receives, via an antennaA201, a radio signal transmitted by the transmit station of FIG. 39 andrelayed by a satellite (repeater station). A relationship between thetransmit station, repeated station, and receive apparatus (terminal) isdescribed in the next embodiment.

An RF receiver A202 performs processing such as frequency conversion andquadrature demodulation on a received radio signal, and outputs abaseband signal.

A demodulator A204 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

A synchronization and channel estimator A214 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

A control information estimator A216 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal. Of importance to the present embodiment isthat a symbol transmitting “transmission mode/slot information” of a“TMCC information symbol group” is demodulated and decoded by thereceive apparatus A200. Thus, the control information estimator A216generates information specifying a coding rate and ring ratio fromvalues of four bits (four bits of control information related to ringratio) decoded based on a table identical to Table 14 stored at thereceive apparatus A200, and outputs the information as a portion of acontrol signal.

A de-mapper A206 receives a post-filter baseband signal, control signal,and estimated signal as input, determines, based on the control signal,a modulation scheme (or transmission method) and ring ratio used by“slots composed by a data symbol group”, calculates, based on thisdetermination, a log-likelihood ratio (LLR) for each bit included in adata symbol from the post-filter baseband signal and the estimatedsignal, and outputs the LLRs. (However, instead of a soft decision valuesuch as an LLR a hard decision value may be outputted, and a softdecision value instead of an LLR may be outputted.)

A de-interleaver A208 receives log-likelihood ratios and control signalas input, accumulates input, performs de-interleaving (permutes data)corresponding to interleaving used by the transmit apparatus, andoutputs a post-de-interleaving log-likelihood ratio.

An error correction decoder A212 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection code used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method. The above describes operationwhen iterative detection is not performed, but the receive apparatus mayperform iterative detection as described for the receiver apparatus ofFIG. 2.

Embodiment B

The present embodiment describes a scheme that can select a ring ratioof (12,4)16APSK for each channel even when a coding rate of errorcorrection code is set to a given value (for example, coding rate set asK). In the following, (12,4)16APSK is described as a modulation schemethat selects ring ratios, but modulation schemes that select ring ratiosare not limited to (12,4)16APSK. Thus, by setting a suitable ring ratiofor each channel, a receive apparatus can achieve high data receptionquality.

FIG. 41 to FIG. 43 illustrate a terrestrial transmit stationtransmitting a transmit signal towards a satellite. FIG. 44 illustratesfrequency allocation of each modulated signal. FIG. 45 and FIG. 46illustrate examples of satellites (repeaters) that receive a signaltransmitted by a terrestrial transmit station and transmit a modulatedsignal towards a terrestrial receive terminal.

Note that ring ratio (for example, (12,4)16APSK ring ratio) has beendefined prior to the present embodiment, and ring ratio may also bereferred to as “radius ratio”.

<Transmit Station>

FIG. 41 illustrates an example of a transmit station having a common(shared) amplifier.

N transmit systems B101_1 to B101_N of FIG. 41 each receive video data,audio data, and the control signal A100 as input.

The control signal A100 specifies code length of error correction code,coding rate, modulation scheme, and ring ratio for each channel. Thismodulation scheme is, for example, specified as (12,4)16APSK.

Transmit systems B101_1 to B101_N generate modulated signals accordingto the control signal A100.

A common (shared) amplifier B102 receives modulated signals #1 to #N asinput, amplifies the modulated signals, and outputs a post-amplificationtransmit signal B103 including the modulated signals #1 to #N.

The transmit signal B103 is composed of a signal of N channels ofmodulated signals #1 to #N and includes a “TMCC information symbolgroup” for each channel (each modulated signal). These “TMCC informationsymbol groups” include ring ratio information in addition to code lengthof error correction code, coding rate and modulation scheme.

Specifically, modulated signal #1 includes “TMCC information symbolgroup” in modulated signal #1 (channel #1), modulated signal #2 includes“TMCC information symbol group” in modulated signal #2 (channel #2), . .. , modulated signal #N includes “TMCC information symbol group” inmodulated signal #N (channel #N).

Transmit signal B103 is transmitted via antenna B104.

FIG. 42 illustrates an example of a transmit station having an amplifierfor each transmit system channel.

N amplifiers B201_1 to B201_N amplify a modulated signal inputtedthereto, and output transmit signals B202_1 to B202_N. Transmit signalsB202_1 to B202_N are transmitted via antennas B203_1 to B203_N.

The transmit station of FIG. 43 is an example of a transmit station thathas an amplifier for each transmit system channel, but transmits aftermixing by a mixer.

A mixer B301 mixes post-amplification modulated signals outputted fromthe amplifiers B201_1 to B201_N, and transmits a post-mixing transmitsignal B302 via an antenna B303.

<Frequency Allocation of Each Modulated Signal>

FIG. 44 illustrates an example of frequency allocation of signals(transmit signals or modulated signals) B401_1 to B401_N. In FIG. 44,the horizontal axis is frequency and the vertical axis is power. Asillustrated in FIG. 44, B401_1 indicates a position on a frequency axisof transmit signal #1 (modulated signal #1) in FIG. 41, FIG. 42, andFIG. 43; B401_2 indicates a position on the frequency axis of transmitsignal #2 (modulated signal #2) in FIG. 41, FIG. 42, and FIG. 43; . . .; and B401_N indicates a position on the frequency axis of transmitsignal #N (modulated signal #N) in FIG. 41, FIG. 42, and FIG. 43.

<Satellite>

Referring to the satellite of FIG. 45, a receive antenna B501 receives asignal transmitted by a transmit station, and outputs a receive signalB502. Here, the receive signal B502 includes components of modulatedsignal #1 to modulated signal #N in FIG. 41, FIG. 42, FIG. 43, and FIG.44.

B503 in FIG. 45 is a radio processor. The radio processor B503 includesradio processing B503_1 to B503_N.

Radio processing B503_1 receives the receive signal B502 as input,performs signal processing such as amplification and frequencyconversion with respect to components of modulated signal #1 in FIG. 41,FIG. 42, FIG. 43, and FIG. 44, and outputs a post-signal processingmodulated signal #1.

Likewise, radio processing B503_2 receives the receive signal B502 asinput, performs signal processing such as amplification and frequencyconversion with respect to components of modulated signal #2 in FIG. 41,FIG. 42, FIG. 43, and FIG. 44, and outputs a post-signal processingmodulated signal #2.

. . .

Likewise, radio processing B503_N receives the receive signal B502 asinput, performs signal processing such as amplification and frequencyconversion with respect to components of modulated signal #N in FIG. 41,FIG. 42, FIG. 43, and FIG. 44, and outputs a post-signal processingmodulated signal #N.

An amplifier B504_1 receives the post-signal processing modulated signal#1 as input, amplifies the post-signal processing modulated signal #1,and outputs a post-amplification modulated signal #1.

An amplifier B504_2 receives the post-signal processing modulated signal#2 as input, amplifies the post-signal processing modulated signal #2,and outputs a post-amplification modulated signal #2.

. . .

An amplifier B504_N receives the post-signal processing modulated signal#N as input, amplifies the post-signal processing modulated signal #N,and outputs a post-amplification modulated signal #N.

Thus, each post-amplification modulated signal is transmitted via arespective one of antennas B505_1 to B505_N. (A transmitted modulatedsignal is received by a terrestrial terminal.) Here, frequencyallocation of signals transmitted by a satellite (repeater) is describedwith reference to FIG. 44.

As previously described, referring to FIG. 44, B401_1 indicates aposition on the frequency axis of transmit signal #1 (modulated signal#1) in FIG. 41, FIG. 42, and FIG. 43; B401_2 indicates a position on thefrequency axis of transmit signal #2 (modulated signal #2) in FIG. 41,FIG. 42, and FIG. 43; . . . ; and B401_N indicates a position on thefrequency axis of transmit signal #N (modulated signal #N) in FIG. 41,FIG. 42, and FIG. 43. Here, a frequency band being used is assumed to bea GHz.

Referring to FIG. 44, B401_1 indicates a position on the frequency axisof modulated signal #1 transmitted by the satellite (repeater) in FIG.45; B401_2 indicates a position on the frequency axis of modulatedsignal #2 transmitted by the satellite (repeater) in FIG. 45; . . . ;and B401_N indicates a position on the frequency axis of modulatedsignal #N transmitted by the satellite (repeater) in FIG. 45. Here, afrequency band being used is assumed to be β GHz.

A satellite in FIG. 46 is different from the satellite in FIG. 45 inthat a signal is transmitted after mixing at a mixer B601. Thus, themixer B601 receives a post-amplification modulated signal #1, apost-amplification modulated signal #2, . . . , a post-amplificationmodulated signal #N as input, and generates a post-mixing modulatedsignal. Here, the post-mixing modulated signal includes a modulatedsignal #1 component, a modulated signal #2 component, . . . , and amodulated signal #N component, frequency allocation is as in FIG. 44,and is a signal in β GHz.

<Ring Ratio Selection>

Referring to the satellite systems described in FIG. 41 to FIG. 46,(12,4)16APSK ring ratio (radius ratio) is described as being selectedfor each channel from channel #1 to channel #N.

For example, when a code length (block length) of error correction codeis X bits, among a plurality of selectable coding rates, a coding rate A(for example, 3/4) is selected.

Referring to the satellite systems in FIG. 45 and FIG. 46, whendistortion of the amplifiers B504_1, B504_2, . . . , B504_N is low(linearity of input and output is high), even when a ring ratio (radiusratio) of (12,4)16APSK is uniquely defined, as long as a suitable valueis determined a (terrestrial) terminal (receive apparatus) can achievehigh data reception quality.

In satellite systems, amplifiers that can achieve high output are usedin order to transmit modulated signals to terrestrial terminals. Thus,high-distortion amplifiers (linearity of input and output is low) areused, and the likelihood of distortion varying between amplifiers ishigh (distortion properties (input/output properties) of the amplifiersB504_1, B504_2, . . . , B504_N are different).

In this case, use of suitable (12,4)16APSK ring ratios (radius ratios)for each amplifier, i.e., selecting a suitable (12,4)16APSK ring ratio(radius ratio) for each channel, enables high data reception quality foreach channel at a terminal. The transmit stations in FIG. 41, FIG. 42,and FIG. 43 perform this kind of setting by using the control signalA100.

Accordingly, information related to (12,4)16APSK ring ratios is includedin, for example, control information such as TMCC that is included ineach modulated signal (each channel). (This point is described in theprevious embodiment.)

Accordingly, when the (terrestrial) transmit station in FIG. 41, FIG.42, and FIG. 43 uses (12,4)16APSK as a modulation scheme of a datasymbol of modulated signal #1, ring ratio information of the(12,4)16APSK is transmitted as a portion of control information.

Likewise, when the (terrestrial) transmit station in FIG. 41, FIG. 42,and FIG. 43 uses (12,4)16APSK as a modulation scheme of a data symbol ofmodulated signal #2, ring ratio information of the (12,4)16APSK istransmitted as a portion of control information.

Likewise, when the (terrestrial) transmit station in FIG. 41, FIG. 42,and FIG. 43 uses (12,4)16APSK as a modulation scheme of a data symbol ofmodulated signal #N, ring ratio information of the (12,4)16APSK istransmitted as a portion of control information.

A coding rate of error correction code used in modulated signal #1, acoding rate of error correction code used in modulated signal #2, . . ., and a coding rate of error correction code used in modulated signal #Nmay be identical.

<Receive Apparatus>

A receive apparatus is described that corresponds to the transmissionmethod of the present embodiment.

The receive apparatus (terminal) A200 of FIG. 40 receives, via theantenna A201, a radio signal transmitted by the transmit station in FIG.41 and FIG. 42 and relayed by a satellite (repeater station). The RFreceiver A202 performs processing such as frequency conversion andquadrature demodulation on a received radio signal, and outputs abaseband signal.

The demodulator A204 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

The synchronization and channel estimator A214 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

The control information estimator A216 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal. Of importance to the present embodiment isthat a symbol transmitting “TMCC information symbol group” informationis demodulated and decoded by the receive apparatus A200. Thus, thecontrol information estimator A216 generates information specifying acode length of error correction code, coding rate, modulation scheme,and ring ratio per channel, from values decoded at the receive apparatusA200, and outputs the information as a portion of a control signal.

The de-mapper A206 receives a post-filter baseband signal, controlsignal, and estimated signal as input, determines, based on the controlsignal, a modulation scheme (or transmission method) and ring ratio usedby “slots composed by a data symbol group”, calculates, based on thisdetermination, a log-likelihood ratio (LLR) for each bit included in adata symbol from the post-filter baseband signal and the estimatedsignal, and outputs the LLRs. (However, instead of a soft decision valuesuch as an LLR a hard decision value may be outputted, and a softdecision value may be outputted instead of an LLR.) The de-interleaverA208 receives log-likelihood ratios and a control signal as input,accumulates input, performs de-interleaving (permutes data)corresponding to interleaving used by the transmit apparatus, andoutputs a post-de-interleaving log-likelihood ratio.

The error correction decoder A212 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection code used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method. The above describes operationwhen iterative detection is not performed, but the receive apparatus mayperform iterative detection as described for the receiver apparatus ofFIG. 2.

A method of generating ring ratio information included in controlinformation is not limited to the embodiment described prior to thepresent embodiment, and information related to ring ratios may betransmitted by any means.

Embodiment C

The present embodiment describes signaling (method of transmittingcontrol information) for notifying a terminal of a ring ratio (forexample (12,4)16APSK ring ratio).

Note that ring ratio (for example, (12,4)16APSK ring ratio) has beendefined prior to the present embodiment, and ring ratio may also bereferred to as “radius ratio”.

Signaling as above can be performed by using bits included in a “TMCCinformation symbol group” as described in the present description.

In the present embodiment, an example of configuring a “TMCC informationsymbol group” is based on Transmission System for Advanced Wide BandDigital Satellite Broadcasting, ARIB Standard STD-B44, Ver. 1.0(Non-Patent Literature 2).

Information related to ring ratios for a transmit station to notify aterminal via a satellite (repeater) may accompany use of the 3614 bitsof “extended information” within a “TMCC information symbol group”described with reference to FIG. 18. (This point is also disclosed inTransmission System for Advanced Wide Band Digital SatelliteBroadcasting, ARIB Standard STD-B44, Ver. 1.0 (Non-Patent Literature2).) This is illustrated in FIG. 47.

Extended information in FIG. 47 is a field used for conventional TMCCextended information, and is composed of 16 bits of an extendedidentifier and 3598 bits of an extended region. In “extendedinformation” of TMCC in FIG. 47, when “scheme A” is applied, theextended identifier is all “0” (all 16 bits are zero) and the 3598 bitsof the extended region are “1”.

Further, when “scheme B” is applied, bits of the extended identifierhave values other than all “0”, i.e., values other than“0000000000000000”, as TMCC information is extended. Whether scheme A orscheme B is applied may for example be determined by user settings.

“Scheme A” is a transmission scheme (for example, satellite digitalbroadcast) that determines a ring ratio when a coding rate of errorcorrection code is set to a given value. (Ring ratio is uniquelydetermined when a coding rate of error correction code to be used isdetermined.)

“Scheme B” is a transmission scheme (for example, satellite digitalbroadcast) that can select a ring ratio to use from a plurality of ringratios each time a coding rate of error correction code is set to agiven value.

The following describes examples of signaling performed by a transmitstation, with reference to FIG. 48 to FIG. 52, but in all the examplesthe following bits are used in signaling.

d₀: Indicates a scheme of satellite broadcasting.

c₀c₁c₂c₃: Indicate a table.

b₀b₁b₂b₃: Indicate coding rate (may also indicate ring ratio).

x₀x₁x₂x₃x₄x₅: Indicate ring ratio.

y₀y₁y₂y₃y₄y₅: Indicate difference of ring ratio.

Detailed description of the above bits is provided later.

The “coding rate” illustrated in FIG. 48, FIG. 49, FIG. 50, FIG. 51, andFIG. 52 is coding rate of error correction code, and although values of41/120, 49/120, 61/120, and 109/120 are specifically illustrated, thesevalue may be approximated as 41/120-1/3, 49/120-2/5, 61/120-1/2, and109/120-9/10.

The following describes <Example 1> to <Example 5>.

Referring to extended information in FIG. 47, “scheme A” is selectedwhen all bits of the extended identifier are “0” (all 16 bits are zero)and all 3598 bits of the extended region are “1”.

First, a case is described in which a transmit apparatus (transmitstation) transmits a modulated signal using “scheme A”.

When a transmit apparatus (transmit station) selects (12,4)16APSK as amodulation scheme, a relationship between coding rate of errorcorrection code and ring ratio of (12,4)16APSK is as follows.

TABLE 15 Relationship between coding rate and (12, 4)16APSK ring ratio(radius ratio) when “scheme A” is selected. Ring Coding rate(approximate value) ratio 41/120 (1/3) 3.09 49/120 (2/5) 2.97 61/120(1/2) 3.93 73/120 (3/5) 2.87 81/120 (2/3) 2.92 89/120 (3/4) 2.97 97/120(4/5) 2.73 101/120 (5/6)  2.67 105/120 (7/8)  2.76 109/120 (9/10) 2.69

Accordingly, setting all bits of TMCC extended identifier to “0” (all 16bits are zero) and setting all 3598 bits of TMCC extended region to “1”(a transmit apparatus transmits these values) enables a receiveapparatus to determine that “scheme A” is selected, and further, codingrate information of error correction code is transmitted as a portion ofTMCC. A receive apparatus can determine a (12,4)16APSK ring ratio fromthis information when (12,4)16APSK is used as a modulation scheme.

Specifically, b₀, b₁, b₂, and b₃ are used as described above. Arelationship between b₀ b₁, b₂, b₃, and coding rate of error correctioncode is as follows.

TABLE 16 Relationship between b₁, b₂, b₃, b₄ and coding rate of errorcorrection code Coding rate b₀b₁b₂b₃ (approximate value) 0000 41/120(1/3) 0001 49/120 (2/5) 0010 61/120 (1/2) 0011 73/120 (3/5) 0100 81/120(2/3) 0101 89/120 (3/4) 0110 97/120 (4/5) 0111 101/120 (5/6)  1000105/120 (7/8)  1001 109/120 (9/10)

As in Table 16, when a transmit apparatus (transmit station) uses 41/120as a coding rate of error correction code, (b₀b₁b_(b2)b₃)=(0000).Further, when 49/120 is used as a coding rate of error correction code,(b₀b₁b₂b₃)=(0001), . . . , when 109/120 is used as a coding rate oferror correction code, (b₀b₁b₂b₃)=(1001). As a portion of TMCC, b₀, b₁,b₂, and b₃ are transmitted.

Accordingly, the following table can be made.

TABLE 17 Relationship between b₀, b₁, b₂, b₃, coding rate of errorcorrection code, and ring ratio Coding rate Ring b₀b₁b₂b₃ (approximatevalue) ratio 0000 41/120 (1/3) 3.09 0001 49/120 (2/5) 2.97 0010 61/120(1/2) 3.93 0011 73/120 (3/5) 2.87 0100 81/120 (2/3) 2.92 0101 89/120(3/4) 2.97 0110 97/120 (4/5) 2.73 0111 101/120 (5/6)  2.67 1000 105/120(7/8)  2.76 1001 109/120 (9/10) 2.69

As can be seen from Table 17:

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0000), a coding rate of error correction code is 41/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 3.09.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0001), a coding rate of error correction code is 49/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 2.97.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0010), a coding rate of error correction code is 61/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 3.93.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0011), a coding rate of error correction code is 73/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 2.87.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0100), a coding rate of error correction code is 81/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 2.92.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0101), a coding rate of error correction code is 89/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 2.97.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0110), a coding rate of error correction code is 97/120, andwhen (12,4)16APSK is used, a ring ratio (radius ratio) is 2.73.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(0111), a coding rate of error correction code is 101/120,and when (12,4)16APSK is used, a ring ratio (radius ratio) is 2.67.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(1000), a coding rate of error correction code is 105/120,and when (12,4)16APSK is used, a ring ratio (radius ratio) is 2.76.

When a transmit apparatus (transmit station) is set to(b₀b₁b₂b₃)=(1001), a coding rate of error correction code is 109/120,and when (12,4)16APSK is used, a ring ratio (radius ratio) is 2.69.

Accordingly, a transmit apparatus (transmit station) implements:

-   -   Setting all bits of TMCC extended information to “0” (all 16        bits are zero) and all 3598 bits of TMCC extended region to “1”,        in order to notify a receive apparatus that “scheme A” is being        used.    -   Transmitting b₀b₁b₂b₃ in order that coding rate of error        correction code and (12,4)16APSK can be estimated.

The following describes a case in which a transmit apparatus (of atransmit station) transmits data using “scheme B”.

As described above, when “scheme B” is applied, bits of the extendedidentifier have values other than all “0”, i.e., values other than“0000000000000000”, as TMCC information is extended. Here, as anexample, when “0000000000000001” is transmitted as an extendedidentifier, a transmit apparatus (of a transmit station) transmits datausing “scheme B”.

When the 16 bits of an extended identifier are represented as d₁₅, d₁₄,d₁₃, d₁₂, d₁₁, d₁₀, d₉, d₈, d₇, d₆, d₅, d₄, d₃, d₂, d₁, d₀, in a case inwhich “scheme B” is applied, (d₁₅, d₁₄, d₁₃, d₁₂, d₁₁, d₁₀, d₉, d₈, d₇,d₆, d₅, d₄, d₃, d₂, d₁, d₀)=(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 1). (When “scheme B” is applied as described above it suffices that(d₁₅, d₁₄, d₁₃, d₁₂, d₁₁, d₁₀, d₉, d₈, d₇, d₆, d₅, d₄, d₃, d₂, d₁, d₀)are set to values other than (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0), and are therefore not limited to the example of (d₁₅, d₁₄, d₁₃,d₁₂, d₁₁, d₁₀, d₉, d₈, d₇, d₆, d₅, d₄, d₃, d₂, d₁, d₀)=(0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).)

As specific examples, <Example 1> to <Example 5> are described below.

Example 1

In example 1, a plurality of ring ratios are prepared in a table of(12,4)16APSK ring ratios, and therefore different ring ratios can be setfor one coding rate.

As an example a case is described in which “satellite broadcastingscheme: “scheme B”, coding rate: 41/120, and (12,4)16APSK ring ratio:4.00” are set. (Note that it is assumed that (12,4)16APSK is selected asa modulation scheme.)

As illustrated in FIG. 48, table 1, table 2, . . . , table 16, in otherwords 16 tables, table 1 to table 16, are prepared.

Each table associates (b₀b₁b₂b₃) values as described above, coding ratesof error correction codes, and (12,4)16APSK ring ratios with each other.

For example, in table 1, when a coding rate of error correction code forgenerating a data symbol is 41/120 and a (12,4)16APSK ring ratio is3.09, (b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 2.97, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)16APSK ring ratio is 3.09, (b₀b₁b₂b₃)=(1001).

In table 2, when a coding rate of error correction code for generating adata symbol is 41/120 and a (12,4)16APSK ring ratio is 4.00,(b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 3.91, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)16APSK ring ratio is 3.60, (b₀b₁b₂b₃)=(1001).

. . .

In table 16, when a coding rate of error correction code for generatinga data symbol is 41/120 and a (12,4)16APSK ring ratio is 2.59,(b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 2.50, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)16APSK ring ratio is 2.23, (b₀b₁b₂b₃)=(1001).

In table 1 to table 16, although not described above, b₀b₁b₂b₃ valuesand (12,4)16APSK ring ratios are associated with each of coding rates oferror correction code 41/120, 49/120, 61/120, 73/120, 81/120, 89/120,97/120, 101/120, 105/120, and 109/120.

Further, as illustrated in FIG. 48, association between c₀c₁c₂c₃ valuesand table selected is performed. When table 1 is selected,(c₀,c₁,c₂,c₃)=(0,0,0,0), when table 2 is selected,(c₀,c₁,c₂,c₃)=(0,0,0,1), . . . , and when table 16 is selected,(c₀,c₁,c₂,c₃)=(1,1,1,1).

The following describes a method of setting, for example, “satellitebroadcasting scheme: “scheme B”, coding rate: 41/120, and (12,4)16APSKring ratio: 4.00”.

First, as above, “scheme B” is selected so d₀=“1” is set.

Further, as illustrated in FIG. 48, a first line of table 2 shows acoding rate 41/120 and a (12,4)16APSK ring ratio 4.00, and thereforeb₀b₁b₂b₃=“0000”.

Accordingly, a value c₀c₁c₂c₃=“0001” for indicating table 2 among 16tables, table 1 to 16.

Accordingly, when a transmit apparatus (transmit station) transmits adata symbol when “satellite broadcasting scheme: “scheme B”, codingrate: 41/120, and (12,4)16APSK ring ratio: 4.00”, the transmit apparatustransmits d₀=“1”, b₀b₁b₂b₃=“0000”, and c₀c₁c₂c₃=“0001” controlinformation (a portion of TMCC information) along with the data symbol.Note that, as control information, transmission is also required ofcontrol information indicating that a modulation scheme of the datasymbol is (12,4)16APSK.

In other words, in <Example 1>:

-   -   A plurality of tables are prepared that associates b₀b₁b₂b₃        values and (12,4)16APSK ring ratios with each of coding rates of        error correction code 41/120, 49/120, 61/120, 73/120, 81/120,        89/120, 97/120, 101/120, 105/120, and 109/120.    -   c₀c₁c₂c₃ indicates a used table and is transmitted by a transmit        apparatus (transmit station).

Thus, a transmit apparatus transmits ring ratio information of(12,4)16APSK used to generate a data symbol.

A method of setting (12,4)16APSK ring ratios when a transmit apparatus(transmit station) uses “scheme A” is as described prior to thedescription of <Example 1>.

Example 2

Example 2 is a modification of <Example 1>.

The following describes a case in which a transmit apparatus (of atransmit station) selects “scheme B”. Here, a transmit apparatus(transmit station) selects “scheme B”, and therefore d₀=“1” is set, asindicated in FIG. 49.

Subsequently, the transmit apparatus (transmit station) sets a value ofz₀. When a (12,4)16APSK ring ratio is set by the same method as “schemeA”, z₀=0 is set. When z₀=0 is set, a coding rate of error correctioncode is determined from b₀, b₁, b₂, b₃ in table 16 and (12,4)16APSK ringratio is determined from table 15. (See Table 17)

When a (12,4)16APSK ring ratio is set by the same method as in Example1, z₀=1 is set. Thus, (12,4)16APSK ring ratio is not determined based ontable 15, but is determined in the way described in Example 1.

As an example a case is described in which “satellite broadcastingscheme: “scheme B”, coding rate: 41/120, and (12,4)16APSK ring ratio:4.00” are set. (Note that it is assumed that (12,4)16APSK is selected asa modulation scheme and z₀=1.)

As illustrated in FIG. 49, table 1, table 2, . . . , table 16, in otherwords 16 tables, table 1 to table 16, are prepared.

Each table associates (b₀b₁b₂b₃) values as described above, coding ratesof error correction code, and (12,4)16APSK ring ratios with each other.

For example, in table 1, when a coding rate of error correction code forgenerating a data symbol is 41/120 and a (12,4)16APSK ring ratio is3.09, (b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 2.97, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)16APSK ring ratio is 3.09, (b₀b₁b₂b₃)=(1001).

In table 2, when a coding rate of error correction code for generating adata symbol is 41/120 and a (12,4)16APSK ring ratio is 4.00,(b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 3.91, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)16APSK ring ratio is 3.60, (b₀b₁b₂b₃)=(1001).

In table 16, when a coding rate of error correction code for generatinga data symbol is 41/120 and a (12,4)16APSK ring ratio is 2.59,(b₀b₁b₂b₃)=(0000). In the same way, when a coding rate of errorcorrection code for generating a data symbol is 49/120 and a(12,4)16APSK ring ratio is 2.50, (b₀b₁b₂b₃)=(0001) . . . . . When acoding rate of error correction code for generating a data symbol is109/120 and a (12,4)12APSK ring ratio is 2.23, (b₀b₁b₂b₃)=(1001).

In table 1 to table 16, although not described above, b₀b₁b₂b₃ valuesand (12,4)16APSK ring ratios are associated with each of coding rates oferror correction code 41/120, 49/120, 61/120, 73/120, 81/120, 89/120,97/120, 101/120, 105/120, and 109/120.

Further, as illustrated in FIG. 49, association between c₀c₁c₂c₃ valuesand table selected is performed. When table 1 is selected,(c₀,c₁,c₂,c₃)=(0,0,0,0), when table 2 is selected,(c₀,c₁,c₂,c₃)=(0,0,0,1), . . . , and when table 16 is selected,(c₀,c₁,c₂,c₃)=(1,1,1,1).

The following describes a method of setting, for example, “satellitebroadcasting scheme: “scheme B”, coding rate: 41/120, and (12,4)16APSKring ratio: 4.00”.

First, as above, “scheme B” is selected so d₀=“1” is set. Further, z₀=1is set.

Further, as illustrated in FIG. 49, a first line of table 2 shows acoding rate 41/120 and a (12,4)16APSK ring ratio 4.00, and thereforeb₀b₁b₂b₃=“0000”.

Accordingly, a value c₀c₁c₂c₃=“0001” for indicating table 2 among 16tables, table 1 to 16.

Accordingly, when a transmit apparatus (transmit station) transmits adata symbol so that “satellite broadcasting scheme: “scheme B”, codingrate: 41/120, and (12,4)16APSK ring ratio: 4.00”, the transmit apparatustransmits d₀=“1”, z₀=1, b₀b₁b₂b₃=“0000”, and c₀c₁c₂c₃=“0001” controlinformation (a portion of TMCC information) along with the data symbol.Note that, as control information, transmission is also required ofcontrol information indicating that a modulation scheme of the datasymbol is (12,4)16APSK.

A method of setting (12,4)16APSK ring ratios when a transmit apparatus(transmit station) uses “scheme A” is as described prior to thedescription of <Example 1>.

Example 3

Example 3 is characterized by signaling being performed by a valueindicating ring ratio.

First, as in <Example 1> and <Example 2>, a transmit apparatus (transmitstation) transmits a modulated signal by “scheme B”, and therefored₀=“1” is set.

Thus, as illustrated in FIG. 50, values of x₀x₁x₂x₃x₄x₅ and (12,4)16APSKring ratios are associated with each other. For example, as illustratedin FIG. 50, when a transmit apparatus (transmit station) is set so thatwhen (x₀,x₁,x₂,x₃,x₄,x₅)=(0,0,0,0,0,0), (12,4)16APSK ring ratio is setto 2.00, . . . , when (x₀,x₁,x₂,x₃,x₄,x₅)=(1,1,1,1,1,1), (12,4)16APSKring ratio is set to 4.00.

As an example, the following describes a method of setting, for example,“satellite broadcasting scheme: “scheme B”, and (12,4)16APSK ring ratio:2.00”.

In this example, a transmit apparatus (transmit station) setsx₀x₁x₂x₃x₄x₅=“000000” from “relationship between x₀x₁x₂x₃x₄x₅ value and(12,4)16APSK ring ratio” in FIG. 50.

Accordingly, when a transmit apparatus (transmit station) transmits adata symbol so that “satellite broadcast scheme: “scheme B” and(12,4)16APSK ring ratio: 2.00”, the transmit apparatus transmits d₀=“1”and x₀x₁x₂x₃x₄x₅=“000000” control information (a portion of TMCCinformation) along with the data symbol. Note that, as controlinformation, transmission is also required of control informationindicating that a modulation scheme of the data symbol is (12,4)16APSK.

A method of setting (12,4)16APSK ring ratios when a transmit apparatus(transmit station) uses “scheme A” is as described prior to thedescription of <Example 1>.

Example 4

Example 4 implements signaling of a desired (12,4)16APSK ring ratio byb₀b₁b₂b₃, indicating coding rate of error correction code and(12,4)16APSK ring ratio in a main table, and y₀y₁y₂y₃y₄₅, indicatingring ratio difference.

An important point in Example 4 is that the main table illustrated inFIG. 51 is composed of the relationship between b₀,b_(i),b₂,b₃, codingrate of error correction code, and ring ratio from Table 17, in otherwords “scheme A”.

Further characterizing points of Example 4 are described below.

FIG. 51 illustrates a difference table. The difference table is a tablefor difference information from (12,4)16APSK ring ratios set using themain table. Based on the main table, a (12,4)16APSK ring ratio is, forexample, set as h.

Thus, the following is true.

. . .

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(011110), (12,4)16APSK ring ratio is set to h+0.4.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(011111), (12,4)16APSK ring ratio is set to h+0.2.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(100000), (12,4)16APSK ring ratio is set to h+0.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(100001), (12,4)16APSK ring ratio is set to h−0.2.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(100010), (12,4)16APSK ring ratio is set to h−0.4.

Accordingly, a transmit apparatus determines (y₀y₁y₂y₃y₄y₅) and therebydetermines a correction value f with respect to a (12,4)16APSK ringratio h determined by the main table, and sets a (12,4)16APSK ring ratioto h+f.

As an example, the following describes a method of setting “satellitebroadcasting scheme: “scheme B”, coding rate: 41/120, and (12,4)16APSKring ratio: 3.49”.

First, a transmit apparatus selects “scheme B” and therefore setsd₀=“1”.

Subsequently, the transmit apparatus sets b₀b₁b₂b₃=“0000” to selectcoding rate 41/120 from the main table of FIG. 51.

Since the (12,4)16APSK ring ratio corresponding to b₀b₁b₂b₃=“0000” inthe main table is 3.09, the difference between the ring ratio 3.49 to beset and the ring ration 3.09 is 3.49-3.09=+0.4.

Thus, the transmit apparatus sets y₀y₁y₂y₃y₄y₅=“011110”, which indicates“+0.4” in the difference table.

Accordingly, when the transmit apparatus (transmit station) transmits adata symbol so that “satellite broadcasting scheme: “scheme B”, codingrate: 41/120, and (12,4)16APSK ring ratio: 3.49”, the transmit apparatustransmits d₀=“1”, b₀b₁b₂b₃=“0000”, y₀y₁y₂y₃y₄y₅=“011110” controlinformation (a portion of TMCC information) along with the data symbol.Note that, as control information, transmission is also required ofcontrol information indicating that a modulation scheme of the datasymbol is (12,4)16APSK.

Example 4 uses a portion of the main table of “scheme A” even when using“scheme B”, and therefore a portion of “scheme A” is suitable for use in“scheme B”.

Not that a method of setting (12,4)16APSK ring ratios when a transmitapparatus (transmit station) uses “scheme A” is as described prior tothe description of <Example 1>.

In FIG. 51 a single difference table is provided but a plurality ofdifference tables may be provided. For example, difference table 1 todifference table 16 may be provided. Thus, as in FIG. 48 and FIG. 49, adifference table to be used may be selected by c₀c₁c₂c₃. Accordingly, atransmit apparatus sets c₀c₁c₂c₃ in addition to d₀, b₀b₁b₂b₃, andy₀y₁y₂y₃y₄y₅, and transmits c₀c₁c₂c₃ in addition to d₀, b₀b₁b₂b₃, andy₀y₁y₂y₃y₄y₅ as a portion of control information along with a datasymbol.

Further, from a value of y₀y₁y₂y₃y₄y₅ in a difference table being used,a correction value f is obtained for a (12,4)16APSK ring ratio hdetermined by using the main table.

Example 5

Example 5 implements signaling of a desired ring ratio by usingb₀b₁b₂b₃, indicating coding rate of error correction code and(12,4)16APSK ring ratio in a main table, and y₀y₁y₂y₃y₄₅, indicatingring ratio difference.

An important point in Example 5 is that the main table illustrated inFIG. 52 is composed of the relationship between b₀,b_(i),b₂,b₃, codingrate of error correction code, and ring ratio from Table 17, in otherwords “scheme A”.

Further characterizing points of Example 5 are described below.

FIG. 52 illustrates a difference table. The difference table is a tablefor difference information from (12,4)16APSK ring ratios set using themain table. Based on the main table, a (12,4)16APSK ring ratio is, forexample, set as h.

Thus, the following is true.

. . .

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(011110), (12,4)16APSK ring ratio is set to h×1.2.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃y₄y₅)=(011111), (12,4)16APSK ring ratio is set to h×1.1.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃₄y₅)=(100000), (12,4)16APSK ring ratio is set to h×1.0.

When a transmit apparatus (transmit station) sets(y₀y₁y₂₃y₄y₅)=(100001), (12,4)16APSK ring ratio is set to h×0.9.

When a transmit apparatus (transmit station) sets(y₀y₁y₂y₃₄y₅)=(100010), (12,4)16APSK ring ratio is set to h×0.8.

Accordingly, a transmit apparatus determines (y₀y₁y₂y₃y₄y₅) and therebydetermines a correction coefficient g with respect to a (12,4)16APSKring ratio h determined by the main table, and sets a (12,4)16APSK ringratio to h×g.

As an example, the following describes a method of setting “satellitebroadcasting scheme: “scheme B”, coding rate: 41/120, and (12,4)16APSKring ratio: 2.78”.

First, a transmit apparatus selects “scheme B” and therefore setsd₀=“1”.

Subsequently, the transmit apparatus sets b₀b₁b₂b₃=“0000” to selectcoding rate 41/120 from the main table of FIG. 52.

Since the (12,4)16APSK ring ratio corresponding to b₀b₁b₂b₃=“0000” inthe main table is 3.09, the difference indicated by multiplicationbetween the ring ratio to be set 2.78 and 3.09 is 2.78/3.09=0.9.

Thus, the transmit apparatus sets y₀y₁y₂y₃y₄y₅=“100001”, which indicates“×0.9” in the difference table.

Accordingly, when a transmit apparatus (transmit station) transmits adata symbol so that “satellite broadcasting scheme: “scheme B”, codingrate: 41/120, and (12,4)16APSK ring ratio: 2.78”, the transmit apparatustransmits d₀=“1”, b₀b₁b₂b₃=“0000”, and y₀₁y₂y₃y₄y₅=“100001” controlinformation (portion of TMCC information) along with the data symbol.Note that, as control information, transmission is also required ofcontrol information indicating that a modulation scheme of the datasymbol is (12,4)16APSK.

Example 5 uses a portion of the main table of “scheme A” even when using“scheme B”, and therefore a portion of “scheme A” is suitable for use in“scheme B”.

Not that a method of setting (12,4)16APSK ring ratios when a transmitapparatus (transmit station) uses “scheme A” is as described prior tothe description of <Example 1>.

In FIG. 52 a single difference table is provided but a plurality ofdifference tables may be provided. For example, difference table 1 todifference table 16 may be provided. Thus, as in FIG. 48 and FIG. 49, adifference table to be used may be selected by c₀c₁c₂c₃. Accordingly, atransmit apparatus sets c₀c₁c₂c₃ in addition to d₀, b₀b₁b₂b₃, andy₀y₁y₂y₃y₄y₅, and transmits c₀c₁c₂c₃ in addition to d₀, b₀b₁b₂b₃, andy₀y₁y₂y₃y₄y₅ as a portion of control information along with a datasymbol.

Further, from a value of y₀y₁y₂y₃y₄y₅ in a difference table being used,a correction coefficient g is obtained for a (12,4)16APSK ring ratio hdetermined by using the main table.

<Receive Apparatus>

The following describes configuration common to <Example 1> to <Example5> of a receive apparatus corresponding to a transmission method of thepresent embodiment and subsequently describes specific processing foreach example.

The terrestrial receive apparatus (terminal) A200 of FIG. 40 receives,via the antenna A201, a radio signal transmitted by the transmit stationof FIG. 39 and relayed by a satellite (repeater station). The RFreceiver A202 performs processing such as frequency conversion andquadrature demodulation on a received radio signal, and outputs abaseband signal.

The demodulator A204 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

The synchronization and channel estimator A214 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

The control information estimator A216 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal.

Of importance to the present embodiment is that control informationincluded in “TMCC information symbol group” is estimated by the controlinformation estimator A216 and outputted as a control signal, and thatd₀, z₀, c₀c₁c₂c₃, b₀b₁b₂b₃, x₀x₁x₂x₃x₄x₅, and y₀y₁y₂y₃y₄y₅ information,described above, is included in the control signal.

The de-mapper A206 receives a post-filter baseband signal, controlsignal, and estimated signal as input, determines, based on the controlsignal, a modulation scheme (or transmission method) and ring ratio usedby “slots composed by a data symbol group”, calculates, based on thisdetermination, a log-likelihood ratio (LLR) for each bit included in adata symbol from the post-filter baseband signal and the estimatedsignal, and outputs the LLRs. (However, instead of a soft decision valuesuch as an LLR a hard decision value may be outputted, and a softdecision value may be outputted instead of an LLR.)

The de-interleaver A208 receives log-likelihood ratios and a controlsignal as input, accumulates input, performs de-interleaving (permutesdata) corresponding to interleaving used by the transmit apparatus, andoutputs post-de-interleaving log-likelihood ratios.

The error correction decoder A212 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection code used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method. The above describes operationwhen iterative detection is not performed, but the receive apparatus mayperform iterative detection as described for the receiver apparatus ofFIG. 2.

Such a receive apparatus stores tables that are the same as the tablesindicates in <Example 1> to <Example 5>, described above, and, byperforming operations in reverse of that described in <Example 1> to<Example 5>, estimates a satellite broadcasting scheme, coding rate oferror correction code, and (12,4)16APSK ring ratio, and performsdemodulation and decoding. The following describes each exampleseparately.

In the following, the control information estimator A216 of a receiveapparatus is assumed to determine that a modulation scheme of a datasymbol is (12,4)16APSK from TMCC information.

<<Receive Apparatus Corresponding to Example 1>>

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme A”:

When the control information estimator A216 of a receive apparatusobtains d₀=“0”, the control information estimator A216 determines that adata symbol is a symbol transmitted by “scheme A”. By obtaining a valueof b₀b₁b₂b₃, when the data symbol is a (12,4)16APSK symbol, the controlinformation estimator A216 estimates a (12,4)16APSK ring ratio. Thede-mapper A206 performs demodulation of the data symbol based on theabove estimated information.

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme B”:

As illustrated in FIG. 53, the control information estimator A216 of thereceive apparatus estimates “scheme B” from d₀=“1”, and a coding rate oferror correction code 41/120 and (12,4)16APSK ring ratio 4.00 from line1 of table 2 based on c₀c₁c₂c₃=“0001” and b₀b₁b₂b₃=“0000”. The de-mapperA206 performs demodulation of the data symbol based on the aboveestimated information.

<<Receive Apparatus Corresponding to Example 2>>

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme A”:

When the control information estimator A216 of a receive apparatusobtains d₀=“0”, the control information estimator A216 determines that adata symbol is a symbol transmitted by “scheme A”. By obtaining a valueof b₀b₁b₂b₃, when the data symbol is a (12,4)16APSK symbol, the controlinformation estimator A216 estimates a (12,4)16APSK ring ratio. Thede-mapper A206 performs demodulation of the data symbol based on theabove estimated information.

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme B”:

As illustrated in FIG. 54, the control information estimator A216 of thereceive apparatus determines “set to same ring ratio as scheme A” whenobtaining d₀=“1” and z₀=“0”, and estimates a coding rate of errorcorrection code and (12,4)16APSK ring ratio from Table 17 when obtainingb₀b₁b₂b₃. The de-mapper A206 performs demodulation of the data symbolbased on the above estimated information.

Further, as illustrated in FIG. 54, the control information estimatorA216 of the receive apparatus determines “set to ring ratio for schemeB” from d₀=“1” and z₀=“l”, and estimates a coding rate of errorcorrection code 41/120 and (12,4)16APSK ring ratio 4.00 from line 1 oftable 2 based on c₀c₁c₂c₃=“0001” and b₀b₁b₂b₃=“0000”. The de-mapper A206performs demodulation of the data symbol based on the above estimatedinformation.

<<Receive Apparatus Corresponding to Example 3>>

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme A”:

When the control information estimator A216 of a receive apparatusobtains d₀=“0”, the control information estimator A216 determines that adata symbol is a symbol transmitted by “scheme A”. By obtaining a valueof b₀b₁b₂b₃, when the data symbol is a (12,4)16APSK symbol, the controlinformation estimator A216 estimates a (12,4)16APSK ring ratio. Thede-mapper A206 performs demodulation of the data symbol based on theabove estimated information.

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme B”:

As illustrated in FIG. 55, the control information estimator A216 of thereceive apparatus estimates “scheme B” from d₀=“1”, and (12,4)16APSKring ratio 2.00 from x₀x₁x₂x₃x₄x₅=“000000”. The de-mapper A206 performsdemodulation of the data symbol based on the above estimatedinformation.

<<Receive Apparatus Corresponding to Example 4>>

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme A”:

When the control information estimator A216 of a receive apparatusobtains d₀=“0”, the control information estimator A216 determines that adata symbol is a symbol transmitted by “scheme A”. By obtaining a valueof b₀b₁b₂b₃, when the data symbol is a (12,4)16APSK symbol, the controlinformation estimator A216 estimates a (12,4)16APSK ring ratio. Thede-mapper A206 performs demodulation of the data symbol based on theabove estimated information.

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme B”:

As illustrated in FIG. 56, the control information estimator A216 of thereceive apparatus determines that a data symbol is a symbol of “schemeB” from d₀=“1”. Further, the control information estimator A216 of thereceive apparatus estimates a difference of +0.4 fromy₀y₁y₂y₃y₄y₅=“011110”. Further, based on b₀b₁b₂b₃=“0000”, the controlinformation estimator A216 estimates (12,4)16APSK ring ratio 3.09 priorto taking into account difference, and estimates a coding rate of errorcorrection code 41/120. By summing both so that 3.09+0.4=3.49, thecontrol information estimator A216 estimates a (12,4)16APSK ring ratio3.49. The de-mapper A206 performs demodulation of the data symbol basedon the above estimated information.

<<Receive Apparatus Corresponding to Example 5>>

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme A”:

When the control information estimator A216 of a receive apparatusobtains d₀=“0”, the control information estimator A216 determines that adata symbol is a symbol transmitted by “scheme A”. By obtaining a valueof b₀b₁b₂b₃, when the data symbol is a (12,4)16APSK symbol, the controlinformation estimator A216 estimates a (12,4)16APSK ring ratio. Thede-mapper A206 performs demodulation of the data symbol based on theabove estimated information.

-   -   When a transmit apparatus (transmit station) transmits a        modulated signal by “scheme B”:

As illustrated in FIG. 57, the control information estimator A216 of thereceive apparatus determines that a data symbol is a symbol of “schemeB” from d₀=“l”. Further, the control information estimator A216 of thereceive apparatus estimates a difference of ×0.9 fromy₀y₁y₂y₃y₄y₅=“100001”. Further, based on b₀b₁b₂b₃=“0000”, the controlinformation estimator A216 estimates (12,4)16APSK ring ratio 3.09 priorto taking into account difference, and estimates a coding rate of errorcorrection code 41/120. By multiplying both so that 3.09×0.9=2.78, thecontrol information estimator A216 estimates a (12,4)16APSK ring ratio2.78. The de-mapper A206 performs demodulation of the data symbol basedon the above estimated information.

Embodiment D

In the present embodiment, a method of transmitting pilot symbols basedon embodiment C is described.

Note that ring ratio (for example, (12,4)16APSK ring ratio) has beendefined prior to the present embodiment, and ring ratio may also bereferred to as “radius ratio”.

<Example of Pilot Symbols>

In the present embodiment, an example is described of pilot symbolconfiguration in the transmit scheme described in embodiment C (a datasymbol modulation scheme is (12,4)16APSK).

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here.

Interference occurs between code (between symbols) of a modulatedsignal, because of non-linearity of the power amplifier of the transmitapparatus. High data reception quality can be achieved by a receiveapparatus by decreasing this intersymbol interference.

In the present example of pilot symbol configuration, in order to reduceintersymbol interference at a receive apparatus, a transmit apparatustransmits pilot symbols by using a modulation scheme and ring ratio usedin a data symbol.

Accordingly, when a transmit apparatus (transmit station) determines amodulation scheme and ring ratio of a data symbol by any of the methodsof <Example 1> to <Example 5> of embodiment C, the transmit apparatusgenerates and transmits pilot symbols by using the same modulationscheme and ring ratio as the data symbol.

The following illustrates specific examples. However, descriptioncontinues assuming that (12,4)16APSK is selected as a modulation scheme.

In the case of <Example 1> of embodiment C:

When a transmit apparatus (transmit station) transmits a data symbol sothat “satellite broadcasting scheme: “scheme B”, coding rate: 41/120,and (12,4)16APSK ring ratio: 4.00”, d₀=“1”, b₀b₁b₂b₃=“0000”, andc₀c₁c₂c₃=“0001”. Thus, based on “d₀=“1”, b₀b₁b₂b₃=“0000”, andc₀c₁c₂c₃=“0001””, the transmit apparatus sets a modulation scheme andring ratio of pilot symbols to (12,4)16APSK and ring ratio 4.00 (of(12,4)16APSK), respectively.

Accordingly, the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio 4.00; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio 4.00.

Thus, a receive apparatus can estimate intersymbol interference withhigh precision, and can therefore achieve high data reception quality.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset andperform time synchronization using the pilot symbols.

When a transmit apparatus sets separate values for data symbol ringratios, pilot symbols are changed to the same ring ratio as data symbols(a value L) and the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

In the case of <Example 2> of embodiment C:

When a transmit apparatus (transmit station) transmits a data symbol sothat “satellite broadcasting scheme: “scheme B”, coding rate: 41/120,and (12,4)16APSK ring ratio: 4.00”, the transmit apparatus transmitsd₀=“1”, z₀=1, b₀b₁b₂b₃=“0000”, and c₀c₁c₂c₃=“0001” control information(a portion of TMCC information) along with the data symbol. Thus, basedon “d₀=“1”, z₀=1, b₀b₁b₂b₃=“0000”, and c₀c₁c₂c₃=“0001””, the transmitapparatus sets a modulation scheme and ring ratio of pilot symbols to(12,4)16APSK and ring ratio 4.00 (of (12,4)16APSK), respectively.

Accordingly, the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio 4.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio 4.00; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio 4.00.

Thus, a receive apparatus can estimate intersymbol interference withhigh precision, and can therefore achieve high data reception quality.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset andperform time synchronization using the pilot symbols.

When a transmit apparatus sets separate values for data symbol ringratios, pilot symbols are changed to the same ring ratio as data symbols(a value L) and the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

In the case of <Example 3> of embodiment C:

When a transmit apparatus (transmit station) transmits a data symbol sothat “satellite broadcasting scheme: “scheme B” and (12,4)16APSK ringratio: 2.00”, the transmit apparatus transmits d₀=“1” andx₀x₁x₂x₃x₄x₅=“000000” control information (a portion of TMCCinformation) along with the data symbol. Thus, based on “d₀=“1”, andx₀x₁x₂x₃x₄x₅=“000000””, the transmit apparatus sets a modulation schemeand ring ratio of pilot symbols to (12,4)16APSK and ring ratio 2.00 (of(12,4)16APSK), respectively.

Accordingly, the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio 2.00;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio 2.00; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio 2.00.

Thus, a receive apparatus can estimate intersymbol interference withhigh precision, and can therefore achieve high data reception quality.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset andperform time synchronization using the pilot symbols.

When a transmit apparatus sets separate values for data symbol ringratios, pilot symbols are changed to the same ring ratio as data symbols(a value L) and the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

In the case of <Example 4> of embodiment C:

When a transmit apparatus (transmit station) transmits a data symbol sothat “satellite broadcasting scheme: “scheme B”, coding rate: 41/120,and (12,4)16APSK ring ratio: 3.49”, the transmit apparatus transmitsd₀=“1”, b₀b₁b₂b₃=“0000”, and y₀y₁y₂y₃y₄y₅=“011110” control information(portion of TMCC information) along with the data symbol. Thus, based on“d₀=“1”, b₀b₁b₂b₃=“0000”, and y₀y₁y₂y₃y₄y₅=“011110””, the transmitapparatus sets a modulation scheme and ring ratio of pilot symbols to(12,4)16APSK and ring ratio 3.49 (of (12,4)16APSK), respectively.

Accordingly, the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio 3.49;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio 3.49; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio 3.49.

Thus, a receive apparatus can estimate intersymbol interference withhigh precision, and can therefore achieve high data reception quality.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset andperform time synchronization using the pilot symbols.

When a transmit apparatus sets separate values for data symbol ringratios, pilot symbols are changed to the same ring ratio as data symbols(a value L) and the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

In the case of <Example 5> of embodiment C:

When a transmit apparatus (transmit station) transmits a data symbol sothat “satellite broadcasting scheme: “scheme B”, coding rate: 41/120,and (12,4)16APSK ring ratio: 2.78”, the transmit apparatus transmitsd₀=“1”, b₀b₁b₂b₃=“0000”, and y₀y₁y₂y₃y₄y₅=“100001” control information(portion of TMCC information) along with the data symbol. Thus, based on“d₀=“1”, b₀b₁b₂b₃=“0000”, and y₀y₁y₂y₃y₄y₅=“100001””, the transmitapparatus sets a modulation scheme and ring ratio of pilot symbols to(12,4)16APSK and ring ratio 2.78 (of (12,4)16APSK), respectively.

Accordingly, the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio 2.78;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio 2.78; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio 2.78.

Thus, a receive apparatus can estimate intersymbol interference withhigh precision, and can therefore achieve high data reception quality.

Pilot symbols need not be symbols only for estimating intersymbolinterference, and a receive apparatus may estimate a radio wavepropagation environment between a transmit apparatus and the receiveapparatus (channel estimation), and may estimate frequency offset andperform time synchronization using the pilot symbols.

When a transmit apparatus sets separate values for data symbol ringratios, pilot symbols are changed to the same ring ratio as data symbols(a value L) and the transmit apparatus (transmit station) transmits thefollowing, in order, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

Operation of a receive apparatus is described with reference to FIG. 2.

In FIG. 2, 210 indicates a configuration of a receive apparatus. Thede-mapper 214 of FIG. 2 performs de-mapping with respect to mapping of amodulation scheme used by the transmit apparatus, for example obtainingand outputting a log-likelihood ratio for each bit. At this time,although not illustrated in FIG. 2, estimation of intersymbolinterference, estimation of a radio wave propagation environment(channel estimation) between the transmit apparatus and the receiveapparatus, time synchronization with the transmit apparatus, andfrequency offset estimation may be performed in order to preciselyperform de-mapping.

Although not illustrated in FIG. 2, the receive apparatus includes anintersymbol interference estimator, a channel estimator, a timesynchronizer, and a frequency offset estimator. These estimators extractfrom receive signals a portion of pilot symbols, for example, andrespectively perform intersymbol interference estimation, estimation ofa radio wave propagation environment (channel estimation) between thetransmit apparatus and the receive apparatus, time synchronizationbetween the transmit apparatus and the receive apparatus, and frequencyoffset estimation between the transmit apparatus and the receiveapparatus. Subsequently, the de-mapper 214 of FIG. 2 inputs theseestimation signals and, by performing de-mapping based on theseestimation signals, performs, for example, calculation of log-likelihoodratios.

Modulation scheme and ring ratio information used in generating a datasymbol is, as described in embodiment C, transmitted by using controlinformation such as TMCC control information. Thus, because a modulationscheme and ring ratio used in generating pilot symbols is the same asthe modulation scheme and ring ratio used in generating data symbols, areceive apparatus estimates, by a control information estimator, themodulation scheme and ring ratio from control information, and, byinputting this information to the de-mapper 214, estimation ofdistortion of propagation path, etc., is performed from the pilotsymbols and de-mapping of the data symbol is performed.

Further, a transmission method of pilot symbols is not limited to theabove. For example, a transmit apparatus (transmit station) maytransmit, as pilot symbols:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L, a plurality of times;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L, a plurality of times;and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L, a plurality of times.

When the following symbols are each transmitted an equal number oftimes, there is an advantage that a receive apparatus can performprecise estimation of distortion of a propagation path:

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0110] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[0111] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1000] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1001] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1010] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1011] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1100] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1101] of (12,4)16APSK ring ratio L;

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1110] of (12,4)16APSK ring ratio L; and

a symbol of a constellation point (baseband signal) corresponding to[b₃b₂b₁b₀]=[1111] of (12,4)16APSK ring ratio L.

Frame configurations applicable to the present invention are not limitedto the above description. When a plurality of data symbols exist, asymbol for transmitting information related to a modulation scheme usedin generating the plurality of data symbols, and a symbol fortransmitting information related to an error correction scheme (forexample, error correction code used, code length of error correctioncode, coding rate of error correction code, etc.) exist, any arrangementin a frame may be used with respect to the plurality of data symbols,the symbol for transmitting information related to a modulation scheme,and the symbol for transmitting information related to an errorcorrection scheme. Further, symbols other than these symbols, forexample a symbol for preamble and synchronization, pilot symbols, areference symbol, etc., may exist in a frame.

(Supplement)

As a matter of course, a plurality of embodiments described herein maybe implemented in combination.

Herein, “∀” represents a universal quantifier and “∃” represents anexistential quantifier.

Herein, in the case of a complex plane, the unit of phase of theargument, for example, is “radians”.

When a complex plane is used, it can be displayed in polar form as polarcoordinates of complex numbers. When points (a and b) on a complex planeare made to correspond to a complex number z=a+jb (a and b are realnumbers, j is an imaginary unit), when expressing a and b as polarcoordinates (r, θ), a=r×cos θ and b=r×sin θ, the following holds true:

[Math 27]

r=√{square root over (a ² +b ²)}  (Math 27)

Here, r is the absolute value of z (r=|z|), and θ is the argument of z.Thus, z=a+jb is expressed as r×e^(jθ).

Note that, for example, a program executing the above communicationmethod may be stored on read only memory (ROM) and the program may beexecuted by a central processing unit (CPU).

Further, a program executing the above communication method may bestored on a computer-readable non-transitory storage medium, the programstored in the storage medium may be written to random access memory(RAM) of a computer, and the computer may be made to operate accordingto the program.

Further, each configuration such as each embodiment may be implementedtypically as a large scale integration (LSI), which is an integratedcircuit. This may be an individual chip, and an entire configuration orpart of the configuration of an embodiment may be included in one chip.Here, “LSI” is referred to, but according to the degree of integrationthis may be called an integrated circuit (IC), system LSI, super LSI, orultra LSI. Further, methods of integration are not limited to LSI, andmay be implemented by a dedicated circuit or general-purpose processor.After LSI manufacture, a field programmable gate array (FPGA) orreconfigurable processor that allows reconfiguring of connections andsettings of circuit cells within the LSI may be used.

Further, if integrated circuit technology to replace LSI is achievedthrough advancement in semiconductor technology or other derivativetechnology, such technology may of course be used to perform integrationof function blocks. Application of biotechnology, etc., is also apossibility.

The following provides supplemental description of transmission schemes.

In the description of the present invention, FIG. 29 is a diagram inwhich a section performing mapping of, for example, the mapper 708 andthe modulator 710 of FIG. 7 and a section performing bandlimiting areextracted when single carrier transmission is used as a transmissionscheme.

In FIG. 29, a mapper 2902 receives a control signal and a digital signalas input, performs mapping based on information related to a modulationscheme (or transmission method) included in the control signal, andoutputs an in-phase component of a post-mapping baseband signal and aquadrature component of a post-mapping baseband signal.

A bandlimiting filter 2904 a receives the in-phase component of thepost-mapping baseband signal and the control signal as input, sets aroll-off rate included in the control signal, performs bandlimiting, andoutputs an in-phase component of a post-bandlimiting baseband signal.

In the same way, a bandlimiting filter 2904 b receives the quadraturecomponent of the post-mapping baseband signal and the control signal asinput, sets a roll-off rate included in the control signal, performsbandlimiting, and outputs a quadrature component of a post-bandlimitingbaseband signal.

Frequency properties of a bandlimiting filter performing bandlimiting ofa carrier are as in Math (28), below.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Math}\mspace{14mu} 28} \right\rbrack} & \; \\\left\{ \begin{matrix}1 & {{F} \leq {F_{n} \times \left( {1 - \alpha} \right)}} \\\sqrt{\frac{1}{2} + {\frac{1}{2}\sin {\frac{\pi}{2\; F_{n}}\left\lbrack \frac{F_{n} - {F}}{\alpha} \right\rbrack}}} & {{F_{n} \times \left( {1 - \alpha} \right)} \leq {F} \leq {F_{n} \times \left( {1 + \alpha} \right)}} \\0 & {{F} \geq {F_{n} \times \left( {1 + \alpha} \right)}}\end{matrix} \right. & \left( {{Math}\mspace{14mu} 28} \right)\end{matrix}$

In the above formula, F is center frequency of a carrier, F_(n) is aNyquist frequency, and a is a roll-off rate.

Here, in a case in which it is possible that the control signal canchange roll-off rate when transmitting a data symbol, ring ratio mayalso be changed for each modulation scheme/transmission method alongwith changes in roll-off rate. In this case, it is necessary to transmitinformation related to changes in ring ratio such as in the examplesabove. Thus, a receive apparatus can demodulate and decode based on thisinformation.

Alternatively, in a case in which it is possible that the roll-off ratecan be changed when transmitting a data symbol, a transmit apparatustransmits information related to roll-off rate changes as a controlinformation symbol. The control information symbol may be generated by aroll-off rate of a given setting.

(Supplement 2)

Embodiment 12 describes the following.

<Signaling>

In the present embodiment, examples are described of various informationsignaled as TMCC information in order to facilitate reception at thereceive apparatus of a transmit signal used in the transmission schemedescribed in embodiment 10.

Note that the transmit apparatus in the present embodiment is identicalto the transmit apparatus described in embodiment 1 and thereforedescription thereof is omitted here. However, (4,8,4)16APSK is usedinstead of (8,8)16APSK.

FIG. 18 illustrates a schematic of a transmit signal frame of advancedwide band digital satellite broadcasting. However, this is not intendedto be an accurate diagram of a frame of advanced wide band digitalsatellite broadcasting. Note that details are described in embodiment 3,and therefore description is omitted here.

Table 18 illustrates a configuration of modulation scheme information.In table 18, for example, when four bits to be transmitted by a symbolfor transmitting a modulation scheme of a transmission mode of“transmission mode/slot information” of a “TMCC information symbolgroup” are [0001], a modulation scheme for generating symbols of “slotscomposed of a symbol group” is π/2 shift binary phase shift keying(BPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0010], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is quadrature phase shift keying (QPSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0011], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 8 phase shift keying (8PSK).

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0100], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (12,4)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0101], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is (4,8,4)16APSK.

When four bits to be transmitted by a symbol for transmitting amodulation scheme of a transmission mode of “transmission mode/slotinformation” of a “TMCC information symbol group” are [0110], amodulation scheme for generating symbols of “slots composed of a symbolgroup” is 32 amplitude phase shift keying (32APSK).

. . .

TABLE 18 Modulation scheme information Value Assignment 0000 Reserved0001 π/2 shift BPSK 0010 QPSK 0011 8PSK 0100 (12, 4)16APSK 0101 (4, 8,4)16APSK 0110 32APSK 0111 . . . . . . . . . 1111 No scheme assigned

Table 19 illustrates a relationship between coding rates of errorcorrection code and ring ratios when a modulation scheme is(12,4)16APSK. According to R₁ and R₂, used above to representconstellation points of (12,4)16APSK in an I-Q plane, a ring ratioR_((12,4)) of (12,4)16APSK is represented as R_((12,4))=R₂/R₁. In Table19, for example, when four bits to be transmitted by a symbol fortransmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen a symbol for transmitting a modulation scheme of a transmissionmode is indicated to be (12,4)16APSK, a ring ratio R_((12,4)) of(12,4)16APSK is 3.09.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 2.97.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (12,4)16APSK, a ring ratio R_((12,4)) of (12,4)16APSK is 3.93.

. . .

TABLE 19 Relationship between coding rates of error correction code andring ratios when modulation scheme is (12, 4)16APSK Coding rate(approximate Value value) Ring ratio 0000 41/120 (1/3) 3.09 0001 49/120(2/5) 2.97 0010 61/120 (1/2) 3.93 . . . . . . . . . 1111 No schemeassigned —

Table 20 indicates a relationship between coding rate of errorcorrection code and radii/phase, when a modulation scheme is(4,8,4)16APSK.

In Table 20, for example, when four bits to be transmitted by a symbolfor transmitting a coding rate of a transmission mode of “transmissionmode/slot information” of a “TMCC information symbol group” are [0000],a coding rate of error correction code for generating symbols of “slotscomposed of a data symbol group” is 41/120 (≈1/3), and this means thatwhen a symbol for transmitting a modulation scheme of a transmissionmode is indicated to be (4,8,4)16APSK, a radius R₁ is 1.00, a radius R₂is 2.00, a radius R₃ is 2.20, and a phase λ is π/12 radians.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0001], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 49/120 (≈2/5), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (4,8,4)16APSK, a radius R₁ is 1.00, a radius R₂ is 2.10, a radius R₃is 2.20, and a phase λ is π/12 radians.

When four bits to be transmitted by a symbol for transmitting a codingrate of a transmission mode of “transmission mode/slot information” of a“TMCC information symbol group” are [0010], a coding rate of errorcorrection code for generating symbols of “slots composed of a datasymbol group” is 61/120 (≈1/2), and this means that when a symbol fortransmitting a modulation scheme of a transmission mode is indicated tobe (4,8,4)16APSK, a radius R₁ is 1.00, a radius R₂ is 2.20, a radius R₃is 2.30, and a phase λ is π/10 radians.

TABLE 20 Relationship between radii/phases of error correction code andring ratios when modulation scheme is (4, 8, 4)16APSK Coding rate Value(approximate value) Radii and phase 0000 41/120 (1/3) R₁ = 1.00 R₂ =2.00 R₃ = 2.20 λ = π/12 0001 49/120 (2/5) R₁ = 1.00 R₂ = 2.10 R₃ = 2.20λ = π/12 0010 61/120 (1/2) R₁ = 1.00 R₂ = 2.20 R₃ = 2.30 λ = π/10 . . .. . . . . . 1111 No scheme assigned —

<Receive Apparatus>

The following describes operation of a receive apparatus that receives aradio signal transmitted by the transmit apparatus 700, with referenceto the diagram of a receive apparatus in FIG. 19.

The receive apparatus 1900 of FIG. 19 receives a radio signaltransmitted by the transmit apparatus 700 via the antenna 1901. The RFreceiver 1902 performs processing such as frequency conversion andquadrature demodulation on a received radio signal, and outputs abaseband signal.

The demodulator 1904 performs processing such as root roll-off filterprocessing, and outputs a post-filter baseband signal.

The synchronization and channel estimator 1914 receives a post-filterbaseband signal as input, performs time synchronization, frequencysynchronization, and channel estimation, using, for example, a“synchronization symbol group” and “pilot symbol group” transmitted bythe transmit apparatus, and outputs an estimated signal.

The control information estimator 1916 receives a post-filter basebandsignal as input, extracts symbols including control information such asa “TMCC information symbol group”, performs demodulation and decoding,and outputs a control signal.

Of importance in the present embodiment is that a receive apparatusdemodulates and decodes a symbol transmitting “transmission modemodulation scheme” information and a symbol transmitting “transmissionmode coding rate” of “transmission mode/slot information” of a “TMCCinformation symbol group”; and, based on Table 18, Table 19, and Table20, the control information estimator 1916 generates modulation schemeinformation and error correction code scheme (for example, coding rateof an error correction code) information used by “slots composed of adata symbol group”, and generates ring ratio and radii/phase informationwhen a modulation scheme used by “slots composed of a data symbol group”is (12,4)16APSK, (4,8,4)16APSK, or 32APSK, and outputs the informationas a portion of a control signal.

The de-mapper 1906 receives a post-filter baseband signal, controlsignal, and estimated signal as input, determines a modulation scheme(or transmission method) used by “slots composed of a data symbol group”based on the control signal (in this case, when there is a ring ratioand radii/phase, determination with respect to the ring ratio andradii/phase is also performed), calculates, based on this determination,a log-likelihood ratio (LLR) for each bit included in a data symbol fromthe post-filter baseband signal and estimated signal, and outputs thelog-likelihood ratios. (However, instead of a soft decision value suchas an LLR a hard decision value may be outputted, and a soft decisionvalue may be outputted instead of an LLR.)

The de-interleaver 1908 receives log-likelihood ratios as input,accumulates input, performs de-interleaving (permutes data)corresponding to interleaving used by the transmit apparatus, andoutputs a post-de-interleaving log-likelihood ratio.

The error correction decoder 1912 receives post-de-interleavinglog-likelihood ratios and a control signal as input, determines errorcorrection code used (code length, coding rate, etc.), performs errorcorrection decoding based on this determination, and obtains estimatedinformation bits. When the error correction code being used is an LDPCcode, belief propagation (BP) decoding methods such as sum-productdecoding, shuffled belief propagation (BP) decoding, and layered BPdecoding may be used as a decoding method.

The above describes operation when iterative detection is not performed.The following is supplemental description of operation when iterativedetection is performed. Note that a receive apparatus need not implementiterative detection, and a receive apparatus may be a receive apparatusthat performs initial detection and error detection decoding withoutbeing provided with elements related to iterative detection that aredescribed below.

When iterative detection is performed, the error correction decoder 1912outputs a log-likelihood ratio for each post-decoding bit. (Note thatwhen only initial detection is performed, output of a log-likelihoodratio for each post decoding bit is not necessary.)

The interleaver 1910 interleaves log-likelihood ratios for post-decodingbits (performs permutation), and outputs a post-interleavinglog-likelihood ratio.

The de-mapper 1906 performs iterative detection by usingpost-interleaving log-likelihood ratios, a post-filter baseband signal,and an estimated signal, and outputs log-likelihood ratios forpost-iterative detection bits.

Subsequently, interleaving and error correction code operations areperformed. Thus, these operations are iteratively performed. In thisway, finally the possibility of achieving a preferable decoding resultis increased.

In the above description, a feature thereof is that by a receptionapparatus obtaining a symbol for transmitting a modulation scheme of atransmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group” and a symbol for transmitting a coding rate ofa transmission mode of “transmission mode/slot information” of a “TMCCinformation symbol group”, a modulation scheme, coding rate of errordetection coding, and, when a modulation scheme is 16APSK, 32APSK, ringratios and radii/phases are estimated and demodulation and decodingoperations become possible.

The above describes frame configuration of FIG. 18, but frameconfigurations applicable to the present invention are not limited tothe above description. When a plurality of data symbols exist, a symbolfor transmitting information related to a modulation scheme used ingenerating the plurality of data symbols, and a symbol for transmittinginformation related to an error correction scheme (for example, errorcorrection code used, code length of error correction code, coding rateof error correction code, etc.) exist, any arrangement in a frame may beused with respect to the plurality of data symbols, the symbol fortransmitting information related to a modulation scheme, and the symbolfor transmitting information related to an error correction scheme.Further, symbols other than these symbols, for example a symbol forpreamble and synchronization, pilot symbols, a reference symbol, etc.,may exist in a frame.

In addition, as a method different to that described above, a symboltransmitting information related to ring ratios and radii/phases mayexist, and the transmit apparatus may transmit the symbol. An example ofa symbol transmitting information related to ring ratios andradii/phases is illustrated below.

TABLE 21 Examples of symbol transmitting information related to ringratios and radii/phases Value Assignment 00000 (12, 4)16APSK ring ratio4.00 00001 (12, 4)16APSK ring ratio 4.10 00010 (12, 4)16APSK ring ratio4.20 00011 (12, 4)16APSK ring ratio 4.30 00100 (4, 8, 4)16APSK R₁ =1.00, R₂ = 2.00, R₃ = 2.20, λ = π/12 00101 (4, 8, 4)16APSK R₁ = 1.00, R₂= 2.10, R₃ = 2.20, λ = π/12 00110 (4, 8, 4)16APSK R₁ = 1.00, R₂ = 2.20,R₃ = 2.30, λ = π/10 00111 (4, 8, 4)16APSK R₁ = 1.00, R₂ = 2.20, R₃ =2.30, λ = π/12 . . . . . . 11111 . . .

In Table 21, when [00000] is transmitted by a symbol transmittinginformation related to ring ratio and radii/phase, a data symbol is asymbol of “(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.10”.

When [00010] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.20”.

When [00011] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.30”.

When [00100] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.00, R₃=2.20, λ=π/12”.

When [00101] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.10, R₃=2.20, λ=π/12”.

When [00110] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.20, R₃=2.30, λ=π/10”.

When [00111] is transmitted by a symbol transmitting information relatedto ring ratio and radii/phase, a data symbol is a symbol of“(4,8,4)16APSK R₁=1.00, R₂=2.20, R₃=2.30, λ=π/12”.

Thus, by obtaining a symbol transmitting information related to ringratio and radii/phases, a receive apparatus can estimate a ring ratioand radii/phases used by a data symbol, and therefore demodulation anddecoding of the data symbol becomes possible.

Further, ring ratio and radii/phases information may be included in asymbol for transmitting a modulation scheme. An example is illustratedbelow.

TABLE 22 Modulation scheme information Value Assignment 00000 (12,4)16APSK ring ratio 4.00 00001 (12, 4)16APSK ring ratio 4.10 00010 (12,4)16APSK ring ratio 4.20 00011 (12, 4)16APSK ring ratio 4.30 00100 (4,8, 4)16APSK R₁ = 1.00, R₂ = 2.00, R₃ = 2.20, λ = π/12 00101 (4, 8,4)16APSK R₁ = 1.00, R₂ = 2.10, R₃ = 2.20, λ = π/12 00110 (4, 8, 4)16APSKR₁ = 1.00, R₂ = 2.20, R₃ = 2.30, λ = π/10 00111 (4, 8, 4)16APSK R₁ =1.00, R₂ = 2.20, R₃ = 2.30, λ = π/12 . . . . . . 11101 8PSK 11110 QPSK11111 π/2 shift BPSK

In Table 22, when [00000] is transmitted by a symbol transmittingmodulation scheme information, a data symbol is a symbol of“(12,4)16APSK ring ratio 4.00”.

Further, the following is true.

When [00001] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.10”.

When [00010] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.20”.

When [00011] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(12,4)16APSK ring ratio4.30”.

When [00100] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.00, R₃=2.20, λ=π/12”.

When [00101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.10, R₃=2.20, λ=π/12”.

When [00110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.20, R₃=2.30, λ=π/10”.

When [00111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “(4,8,4)16APSK R₁=1.00,R₂=2.20, R₃=2.30, λ=π/12”.

When [11101] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “8PSK”.

When [11110] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “QPSK”.

When [11111] is transmitted by a symbol transmitting modulation schemeinformation, a data symbol is a symbol of “π/2 shift BPSK”.

Thus, by obtaining a symbol transmitting modulation scheme information,a receive apparatus can estimate a modulation scheme, ring ratio, radii,and phases used by a data symbol, and therefore demodulation anddecoding of the data symbol becomes possible.

Note that in the above description, examples are described including“(12,4)16APSK” and “(4,8,4)16APSK” as selectable modulation schemes(transmission methods), but modulation schemes (transmission methods)are not limited to these examples. In other words, other modulationschemes may be selectable.

In embodiment 12, transmission of control information is described in acase in which two different mapping patterns, “(12,4)16APSK” and“(4,8,4)16APSK”, are selectable as 16APSK schemes transmitting four bitsof data in one symbol. This may be re-stated as:

“A method comprising: generating a data symbol by using a modulationscheme selected from a plurality of modulation schemes including a firstmodulation scheme and a second modulation scheme; and transmitting thegenerated data symbol and control information indicating the selectedmodulation scheme, wherein:

(i) mapping of the first modulation scheme and mapping of the secondmodulation scheme each have the same number of constellation points aseach other, the number of constellation points being selected accordingto transmit data, and

(ii) the number of constellation points in a series is different betweenthe mapping of the first modulation scheme and the mapping of the secondmodulation scheme, the series being the number of constellation pointsarranged on a plurality of concentric circles having the origin of anin-phase (I)-quadrature-phase (Q) plane as the center thereof, from acircle having the largest radius (amplitude component) to a circlehaving the smallest radius.”

Here, the number of constellation points selected according to transmitdata is, for example, 16 in the case of “(12,4)16APSK” and 16 in thecase of “(4,8,4)16APSK”. In other words, the number of constellationpoints selected according to transmit data is 16 for both “(12,4)16APSK”and “(4,8,4)16APSK”, and they satisfy condition (i).

Further, the number of constellation points arranged on a plurality ofconcentric circles having the origin of an in-phase (I)-quadrature-phase(Q) plane as the center thereof, from a circle having the largest radius(amplitude component) to a circle having the smallest radius is, forexample, (12,4) in the case of “(12,4)16APSK”, and (4,8,4) in the caseof “(4,8,4)16APSK”. Thus, the number of constellation points arranged onconcentric circles having the origin of an in-phase (I)-quadrature-phase(Q) plane as the center thereof, from a circle having the largest radius(amplitude component) to a circle having the smallest radius isdifferent between “(12,4)16APSK” and “(4,8,4)16APSK”, satisfyingcondition (ii).

In embodiment 12, transmission of control information in a case in whichtwo different mapping patterns, “(12,4)16APSK” and “(4,8,4)16APSK”, areselectable as 16APSK schemes transmitting four bits of data in onesymbol may further be re-stated as:

“A method comprising: generating a data symbol by using a modulationscheme selected from a plurality of modulation schemes including a firstmodulation scheme and a second modulation scheme; and transmitting thegenerated data symbol and control information indicating the selectedmodulation scheme, wherein:

(i) mapping of the first modulation scheme and mapping of the secondmodulation scheme each have the same number of constellation points aseach other, the number of constellation points being selected accordingto transmit data,

(ii) the number of constellation points in a series is different betweenthe mapping of the first modulation scheme and the mapping of the secondmodulation scheme, the series being the number of constellation pointsarranged on a plurality of concentric circles having the origin of anin-phase (I)-quadrature-phase (Q) plane as the center thereof, from acircle having the largest radius (amplitude component) to a circlehaving the smallest radius, and

ring ratios, which are ratios of radius (or diameter) of the pluralityof concentric circles, of the first modulation scheme and the secondmodulation scheme are selectable, and the control information indicatesa selected modulation scheme and ring ratio.”

Note that in embodiment 12, “examples are described including“(12,4)16APSK” and “(4,8,4)16APSK” as selectable modulation schemes(transmission methods), but modulation schemes (transmission methods)are not limited to these examples. In other words, other modulationschemes may be selectable”, is disclosed, and of course “(8,8)16APSK”described in embodiment 1 to embodiment 4 may be selected as one of the“other modulation schemes”.

This is because, in embodiment 10 “embodiment 7 describes a method usingNU-16QAM instead of (8,8)16APSK as described in embodiment 1 toembodiment 4, and embodiment 8 describes a method using (4,8,4)16APSKinstead of (8,8)16APSK as described in embodiment 1 to embodiment 4” isdisclosed, and therefore it is clear that a modulation scheme can use“(8,8)16APSK” instead of “(4,8,4)16APSK”.

Further, for “(8,8)16APSK”, the number of constellation points selectedaccording to transmit data is 16 and the number of constellation pointsarranged on a plurality of concentric circles having the origin of anin-phase (I)-quadrature-phase (Q) plane as the center thereof, from acircle having the largest radius (amplitude component) to a circlehaving the smallest radius is (8,8). In other words, selectingmodulation schemes from “(8,8)16APSK” and “(12,4)16APSK” also satisfiesthe above conditions (i) and (ii).

In embodiment 12, when “(8,8)16APSK” is used instead of “(4,8,4)16APSK”,a table is used that replaces the modulation scheme assigned to value0101 of Table 18 with “(8,8)16APSK”. Further, for instance, Table 3illustrated in embodiment 2 can be used instead of Table 20. Likewise, atable is used that replaces the ring ratio information assigned tovalues 00100 to 00111 in Table 21 with ring ratios of “(8,8)16APSK”.Likewise, a table is used that replaces the ring ratio informationassigned to values 00100 to 00111 in Table 22 with ring ratios of“(8,8)16APSK”.

Thus, by obtaining a symbol transmitting modulation scheme information,a receive apparatus can estimate a modulation scheme and ring ratio usedby a data symbol, and therefore demodulation and decoding of the datasymbol becomes possible.

As above, embodiment 12 may be implemented with “(12,4)16APSK” and“(8,8)16APSK” as selectable modulation schemes (transmission methods).Thus, for example, according to linearity (distortion, PAPR, etc.) of apower amplifier used by a transmit apparatus, a more appropriatemodulation scheme and ring ratio can be selected, and thereby thelikelihood is increased of achieving a reduction in power consumption ofthe transmit apparatus and an increase in data reception quality of areceive apparatus.

When multicast (broadcast) transmission is used by a satellite, thedistance between the satellite and a terminal is far, and therefore whenthe satellite transmits a modulated signal, the modulated signal istransmitted at high power and use of a power amplifier having highlinearity is difficult. In order to ameliorate this problem, high powerefficiency can be achieved in a power amplifier of a transmit apparatusby use of APSK that has a lower peak to average power ratio (PAPR) thanquadrature amplitude modulation (QAM), and therefore power consumptionof the transmit apparatus can be improved. Further, as technologyadvances, the likelihood of linearity of transmit power amplifiersimproving is high. When a power amplifier included in a transmitapparatus mounted on a satellite is exchanged due to maintenance, etc.,an increase in linearity of the transmit power amplifier is apossibility. Taking this into consideration, configuring a transmitapparatus so that (12,4)16APSK and (8,8)16APSK ((4,8,4)16APSK) areselectable and ring ratio can be set has the advantage of increasing thelikelihood that both a reduction in power consumption of the transmitapparatus and an increase in data reception quality of a receiveapparatus can be achieved.

Thus, a receive apparatus of a terminal that receives a modulated signaltransmitted from a satellite can estimate data included in the modulatedsignal by receiving control information transmitted as in the abovetables (modulation scheme information, coding rate of error correctioncode, ring ratio, etc.) and setting demodulation (de-mapping) anddecoding (decoding of error correction code).

INDUSTRIAL APPLICABILITY

The transmit apparatus pertaining to the present invention is applicableto communication/broadcast systems having high error correctioncapability error correction code, and can contribute to improvement indata reception quality when iterative detection is performed at areceive apparatus side.

REFERENCE SIGNS LIST

-   200 transmit apparatus

1. (canceled)
 2. (canceled)
 3. A transmit apparatus for transmittingdata by modulation schemes that shift amplitude and phase, the transmitapparatus comprising: a selector that selects a first modulation schemeor a second modulation scheme for each symbol in order, alternatingbetween the first modulation scheme and the second modulation scheme, aconstellation and bit labelling of each constellation point of the firstmodulation scheme being different to a constellation and bit labellingof each constellation point of the second modulation scheme; a mapperthat performs mapping by using constellation points of a selectedmodulation scheme; and a transmitter that transmits a modulated signalobtained by the mapping.